Remove references to 9.4

Some still lingered.

src/test/regress/expected/multi_upsert.out

@@ -1,6 +1,4 @@
 -- this test file aims to test UPSERT feature on Citus
--- note that output of this file for postgresql 9.4 will
--- be full syntax errors, which is expected.
 ALTER SEQUENCE pg_catalog.pg_dist_shardid_seq RESTART 980000;
 ALTER SEQUENCE pg_catalog.pg_dist_jobid_seq RESTART 980000;
 CREATE TABLE upsert_test

src/test/regress/pg_regress_multi.pl

@@ -298,10 +298,6 @@ if ($majorversion eq '9.5')
 {
     push(@arguments, '--bindir', "tmp_check/tmp-bin");
 }
-elsif ($majorversion eq '9.4')
-{
-    push(@arguments, '--psqldir', "tmp_check/tmp-bin");
-}
 else
 {
     die "Citus is not compatible with the detected PostgreSQL version $majorversion";

src/test/regress/sql/multi_upsert.sql

@@ -1,6 +1,4 @@
 -- this test file aims to test UPSERT feature on Citus
--- note that output of this file for postgresql 9.4 will
--- be full syntax errors, which is expected.
 
 
 ALTER SEQUENCE pg_catalog.pg_dist_shardid_seq RESTART 980000;