Disable autovacuum for BRIN test table

This should improve stability in the tests.

Per buildfarm member hyrax (CLOBBER_CACHE_ALWAYS) via Tom Lane.

Discussion: https://postgr.es/m/871534.1597503261@sss.pgh.pa.us

src/test/regress/expected/brin.out

@@ -26,7 +26,7 @@ CREATE TABLE brintest (byteacol bytea,
 	int4rangecol int4range,
 	lsncol pg_lsn,
 	boxcol box
-) WITH (fillfactor=10);
+) WITH (fillfactor=10, autovacuum_enabled=off);
 INSERT INTO brintest SELECT
 	repeat(stringu1, 8)::bytea,
 	substr(stringu1, 1, 1)::"char",

src/test/regress/sql/brin.sql

@@ -26,7 +26,7 @@ CREATE TABLE brintest (byteacol bytea,
 	int4rangecol int4range,
 	lsncol pg_lsn,
 	boxcol box
-) WITH (fillfactor=10);
+) WITH (fillfactor=10, autovacuum_enabled=off);
 
 INSERT INTO brintest SELECT
 	repeat(stringu1, 8)::bytea,