Clean up sloppy maintenance of regression test schedule files.

The partition_join test was added to a parallel group that was already
at the maximum of 20 concurrent tests.  The hash_func test wasn't
added to serial_schedule at all.  The identity and partition_join tests
were added to serial_schedule with the aid of a dartboard, rather than
maintaining consistency with parallel_schedule.

There are proposals afoot to make these sorts of errors harder to make,
but in the meantime let's fix the ones already in place.

Discussion: https://postgr.es/m/a37e9c57-22d4-1b82-1270-4501cd2e984e@2ndquadrant.com

src/test/regress/parallel_schedule

@@ -104,7 +104,7 @@ test: publication subscription
 # ----------
 # Another group of parallel tests
 # ----------
-test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combocid tsearch tsdicts foreign_data window xmlmap functional_deps advisory_lock json jsonb json_encoding indirect_toast equivclass partition_join
+test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combocid tsearch tsdicts foreign_data window xmlmap functional_deps advisory_lock json jsonb json_encoding indirect_toast equivclass
 
 # ----------
 # Another group of parallel tests
@@ -116,7 +116,7 @@ test: plancache limit plpgsql copy2 temp domain rangefuncs prepare without_oid c
 # ----------
 # Another group of parallel tests
 # ----------
-test: identity
+test: identity partition_join
 
 # event triggers cannot run concurrently with any test that runs DDL
 test: event_trigger

src/test/regress/serial_schedule

@@ -79,6 +79,7 @@ test: updatable_views
 test: rolenames
 test: roleattributes
 test: create_am
+test: hash_func
 test: sanity_check
 test: errors
 test: select
@@ -171,13 +172,13 @@ test: conversion
 test: truncate
 test: alter_table
 test: sequence
-test: identity
 test: polymorphism
 test: rowtypes
 test: returning
 test: largeobject
 test: with
 test: xml
+test: identity
+test: partition_join
 test: event_trigger
 test: stats
-test: partition_join