Fix and rename --use-unique-keys option and add TAP test

Cloudberry has --use-unique-keys options since cc797b9.
However, it does not work, at least at current HEAD.
Fix that, and also rename option, to better indicate its use case.
If user does NOT use this option, pgbenc will create unique index.
If use does use this option, pgbench will not. So, rename to
--use-non-unique-keys.

Found during PG16 kernel rebase.

Author: reshke

src/bin/pgbench/pgbench.c

@@ -716,7 +716,7 @@ usage(void)
 		   "  -q, --quiet              quiet logging (one message each 5 seconds)\n"
 		   "  -s, --scale=NUM          scaling factor\n"
 		   "  --foreign-keys           create foreign key constraints between tables\n"
-		   "  --use-unique-keys        make the indexes that are created non-unique indexes\n"
+		   "  --use-non-unique-keys        make the indexes that are created non-unique indexes\n"
 		   "                           (default: unique)\n"
 		   "  --index-tablespace=TABLESPACE\n"
 		   "                           create indexes in the specified tablespace\n"
@@ -4382,7 +4382,11 @@ initCreatePKeys(PGconn *con)
 	int			i;
 	PQExpBufferData query;
 
-	fprintf(stderr, "creating primary keys...\n");
+	if (use_unique_key)
+		fprintf(stderr, "creating primary keys...\n");
+	else
+		fprintf(stderr, "creating non-unique keys...\n");
+
 	initPQExpBuffer(&query);
 
 	for (i = 0; i < lengthof(DDLINDEXes); i++)
@@ -5837,7 +5841,8 @@ main(int argc, char **argv)
 		{"show-script", required_argument, NULL, 10},
 		{"partitions", required_argument, NULL, 11},
 		{"partition-method", required_argument, NULL, 12},
-		{"use-unique-keys", no_argument, &use_unique_key, 1},
+		/* Cloudberry-specific */
+		{"use-non-unique-keys", no_argument, NULL, 13},
 		{NULL, 0, NULL, 0}
 	};
 
@@ -6217,6 +6222,9 @@ main(int argc, char **argv)
 					exit(1);
 				}
 				break;
+			case 13:
+				use_unique_key = 0;
+				break;
 			default:
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);

src/bin/pgbench/t/001_pgbench_with_server.pl

@@ -100,6 +100,19 @@
 	],
 	'pgbench --init-steps');
 
+
+# Test interaction of --init-steps with legacy step-selection options
+$node->pgbench(
+	'--initialize --use-non-unique-keys',
+	0,
+	[qr{^$}],
+	[
+		qr{creating tables},
+		qr{reating non-unique keys},
+		qr{done in \d+\.\d\d s }
+	],
+	'pgbench --use-non-unique-keys');
+
 # Run all builtin scripts, for a few transactions each
 $node->pgbench(
 	'--transactions=5 -Dfoo=bla --client=2 --protocol=simple --builtin=t'