Remove incorrect %s in string

Appears to have been a copy/paste error in the original commit that
moved the messages to fe_utils/.

Author: Tang, Haiying <tanghy.fnst@cn.fujitsu.com>
Backpatch-through: 13
Discussion: https://postgr.es/m/3321cbcea76d4d2c8320a05c19b9304a@G08CNEXMBPEKD05.g08.fujitsu.local

src/fe_utils/cancel.c

@@ -207,7 +207,7 @@ consoleHandler(DWORD dwCtrlType)
 			}
 			else
 			{
-				write_stderr(_("Could not send cancel request: %s"));
+				write_stderr(_("Could not send cancel request: "));
 				write_stderr(errbuf);
 			}
 		}