Convert multi-line SQL comment to /* */ style

The ORDER BY rationale added for the pg_upgrade row-ordering fix used
consecutive -- lines for one continuous remark; convert it to a /* */
block per the repo's comment convention (see the sibling foundation
fix in advanced-testing/foundation).

Author: jnasbyupgrade

test/helpers/create.sql

@@ -99,13 +99,15 @@ SELECT is(
 SELECT skip('role-restore check only applies when this session ran CREATE EXTENSION itself (test_load_mode=fresh)', 1);
 \endif
 
--- ORDER BY is load-bearing, not cosmetic: with no ordering this scans
--- pg_proc in physical order, which happens to match creation order on a
--- fresh CREATE EXTENSION but is NOT preserved by pg_upgrade (its
--- dump/restore reconstructs pg_proc in a different, e.g. name-sorted,
--- order) -- discovered because the pg_upgrade CI leg's "existing" run
--- produced a row-reordered (but otherwise identical) diff against this
--- same query's fresh-install expected output.
+/*
+ * ORDER BY is load-bearing, not cosmetic: with no ordering this scans
+ * pg_proc in physical order, which happens to match creation order on a
+ * fresh CREATE EXTENSION but is NOT preserved by pg_upgrade (its
+ * dump/restore reconstructs pg_proc in a different, e.g. name-sorted,
+ * order) -- discovered because the pg_upgrade CI leg's "existing" run
+ * produced a row-reordered (but otherwise identical) diff against this
+ * same query's fresh-install expected output.
+ */
 SELECT cmp_ok(
       proconfig
       , '@>'