Remove literal backslash from Perl \Q ... \E.

The behavior changed sometime after Perl 5.8.9, and "man perlre" says it
"may lead to confusing results."  Per buildfarm member gaur.  This
repairs commit a7a7be1.

Discussion: https://postgr.es/m/20210629053627.GA2061079@rfd.leadboat.com

Author: nmisch

src/bin/pg_dump/t/002_pg_dump.pl

@@ -1431,7 +1431,7 @@
 	'CREATE ROLE regress_quoted...' => {
 		create_order => 1,
 		create_sql   => 'CREATE ROLE "regress_quoted  \"" role";',
-		regexp       => qr/^\QCREATE ROLE "regress_quoted  \"" role";\E/m,
+		regexp       => qr/^CREATE ROLE "regress_quoted  \\"" role";/m,
 		like         => {
 			pg_dumpall_dbprivs       => 1,
 			pg_dumpall_exclude       => 1,
@@ -3421,7 +3421,7 @@
 			ALTER SCHEMA public OWNER TO "regress_quoted  \"" role";
 			REVOKE ALL ON SCHEMA public FROM "regress_quoted  \"" role";',
 		regexp => qr/^
-			\QREVOKE ALL ON SCHEMA public FROM "regress_quoted  \"" role";\E
+			\QREVOKE ALL ON SCHEMA public FROM "regress_quoted  \E\\""\ role";
 			\n\QREVOKE ALL ON SCHEMA public FROM PUBLIC;\E
 			\n\QGRANT USAGE ON SCHEMA public TO PUBLIC;\E
 			/xm,