Don't drop NOTICE messages in isolation tests.

For its entire existence, isolationtester.c has forced client_min_messages
to WARNING, but that seems like a very poor choice of test design.  It
should be up to individual test scripts to manage whether they emit notices
and to ensure that the results are stable.  (There were no NOTICE messages
in the original set of isolation tests, so this was certainly dead code
when committed, but perhaps it was needed at some earlier point.)

It's possible that the original motivation was due to platform-dependent
variations in the timing of stdout vs. stderr output.  That should be
moot since commits 73bcb76b7/6eda3e9c2, but just in case, adjust
isotesterNoticeProcessor to print to stdout not stderr.  (stderr seems
like the wrong thing anyway: it should be for error printouts not expected
test output.)

Testing shows that the notices in insert-conflict-specconflict are indeed
a bit timing-unstable on very slow machines, so hide them; maybe we can
improve that later.  Also, make the notices in plpgsql-toast a bit less
verbose than the original code would've had them.

Discussion: https://postgr.es/m/14616.1564251339@sss.pgh.pa.us

src/test/isolation/expected/plpgsql-toast.out

@@ -22,7 +22,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'x = %', x;
+    raise notice 'length(x) = %', length(x);
   end;
 $$;
  <waiting ...>
@@ -35,6 +35,7 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(x) = 6000
 step assign1: <... completed>
 
 starting permutation: lock assign2 vacuum unlock
@@ -59,7 +60,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'x = %', x;
+    raise notice 'length(x) = %', length(x);
   end;
 $$;
  <waiting ...>
@@ -72,6 +73,7 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(x) = 6000
 step assign2: <... completed>
 
 starting permutation: lock assign3 vacuum unlock
@@ -97,7 +99,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
  <waiting ...>
@@ -110,6 +112,7 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(r) = 6004
 step assign3: <... completed>
 
 starting permutation: lock assign4 vacuum unlock
@@ -134,7 +137,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
  <waiting ...>
@@ -147,6 +150,7 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(r) = 6004
 step assign4: <... completed>
 
 starting permutation: lock assign5 vacuum unlock
@@ -173,7 +177,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
  <waiting ...>
@@ -186,4 +190,5 @@ step unlock:
 pg_advisory_unlock
 
 t              
+s1: NOTICE:  length(r) = 6002
 step assign5: <... completed>

src/test/isolation/isolationtester.c

@@ -187,18 +187,6 @@ main(int argc, char **argv)
 								 blackholeNoticeProcessor,
 								 NULL);
 
-		/*
-		 * Suppress NOTIFY messages, which otherwise pop into results at odd
-		 * places.
-		 */
-		res = PQexec(conns[i], "SET client_min_messages = warning;");
-		if (PQresultStatus(res) != PGRES_COMMAND_OK)
-		{
-			fprintf(stderr, "message level setup failed: %s", PQerrorMessage(conns[i]));
-			exit(1);
-		}
-		PQclear(res);
-
 		/* Get the backend pid for lock wait checking. */
 		res = PQexec(conns[i], "SELECT pg_catalog.pg_backend_pid()");
 		if (PQresultStatus(res) == PGRES_TUPLES_OK)
@@ -899,7 +887,7 @@ printResultSet(PGresult *res)
 static void
 isotesterNoticeProcessor(void *arg, const char *message)
 {
-	fprintf(stderr, "%s: %s", (char *) arg, message);
+	printf("%s: %s", (char *) arg, message);
 }
 
 /* notice processor, hides the message */

src/test/isolation/specs/insert-conflict-specconflict.spec

@@ -51,6 +51,9 @@ session "s1"
 setup
 {
   SET default_transaction_isolation = 'read committed';
+  -- on very slow machines, the notices come out in unpredictable order,
+  -- so hide them
+  SET client_min_messages = warning;
   SET spec.session = 1;
 }
 step "s1_begin"  { BEGIN; }
@@ -61,6 +64,9 @@ session "s2"
 setup
 {
   SET default_transaction_isolation = 'read committed';
+  -- on very slow machines, the notices come out in unpredictable order,
+  -- so hide them
+  SET client_min_messages = warning;
   SET spec.session = 2;
 }
 step "s2_begin"  { BEGIN; }

src/test/isolation/specs/plpgsql-toast.spec

@@ -40,7 +40,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'x = %', x;
+    raise notice 'length(x) = %', length(x);
   end;
 $$;
 }
@@ -56,7 +56,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'x = %', x;
+    raise notice 'length(x) = %', length(x);
   end;
 $$;
 }
@@ -73,7 +73,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
 }
@@ -89,7 +89,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
 }
@@ -107,7 +107,7 @@ do $$
     delete from test1;
     commit;
     perform pg_advisory_lock(1);
-    raise notice 'r = %', r;
+    raise notice 'length(r) = %', length(r::text);
   end;
 $$;
 }