Revert all new recent changes to add PGXS options for TAP and isolation

A set of failures in buildfarm machines are proving that this is not
quite ready yet because of another set of issues:
- MSVC scripts assume that REGRESS_OPTS can only use top_builddir.  Some
test suites actually finish by using top_srcdir, like pg_stat_statements
which cause the regression tests to never run.
- Trying to enforce top_builddir does not work either when using VPATH
as this is not recognized properly.
- TAP tests of bloom are unstable on various platforms, causing various
failures.

src/makefiles/pgxs.mk

@@ -46,9 +46,6 @@
 #   HEADERS_built_$(MODULE) -- as above but built first (also NOT cleaned)
 #   REGRESS -- list of regression test cases (without suffix)
 #   REGRESS_OPTS -- additional switches to pass to pg_regress
-#   TAP_TESTS -- switch to enable TAP tests
-#   ISOLATION -- list of isolation test cases
-#   ISOLATION_OPTS -- additional switches to pass to pg_isolation_regress
 #   NO_INSTALLCHECK -- don't define an installcheck target, useful e.g. if
 #     tests require special configuration, or don't use pg_regress
 #   EXTRA_CLEAN -- extra files to remove in 'make clean'
@@ -352,12 +349,6 @@ ifeq ($(PORTNAME), win)
 	rm -f regress.def
 endif
 endif # REGRESS
-ifdef TAP_TESTS
-	rm -rf tmp_check/
-endif
-ifdef ISOLATION
-	rm -rf output_iso/ tmp_check_iso/
-endif
 
 ifdef MODULE_big
 clean: clean-lib
@@ -392,47 +383,28 @@ $(test_files_build): $(abs_builddir)/%: $(srcdir)/%
 	$(MKDIR_P) $(dir $@)
 	ln -s $< $@
 endif # VPATH
-endif # REGRESS
 
 .PHONY: submake
 submake:
 ifndef PGXS
 	$(MAKE) -C $(top_builddir)/src/test/regress pg_regress$(X)
-	$(MAKE) -C $(top_builddir)/src/test/isolation all
 endif
 
-# Standard rules to run regression tests including multiple test suites.
-# Runs against an installed postmaster
+# against installed postmaster
 ifndef NO_INSTALLCHECK
 installcheck: submake $(REGRESS_PREP)
-ifdef REGRESS
 	$(pg_regress_installcheck) $(REGRESS_OPTS) $(REGRESS)
 endif
-ifdef ISOLATION
-	$(pg_isolation_regress_installcheck) $(ISOLATION_OPTS) $(ISOLATION)
-endif
-ifdef TAP_TESTS
-	$(prove_installcheck)
-endif
-endif # NO_INSTALLCHECK
 
-# Runs independently of any installation
 ifdef PGXS
 check:
 	@echo '"$(MAKE) check" is not supported.'
 	@echo 'Do "$(MAKE) install", then "$(MAKE) installcheck" instead.'
 else
 check: submake $(REGRESS_PREP)
-ifdef REGRESS
 	$(pg_regress_check) $(REGRESS_OPTS) $(REGRESS)
 endif
-ifdef ISOLATION
-	$(pg_isolation_regress_check) $(ISOLATION_OPTS) $(ISOLATION)
-endif
-ifdef TAP_TESTS
-	$(prove_check)
-endif
-endif # PGXS
+endif # REGRESS
 
 ifndef NO_TEMP_INSTALL
 temp-install: EXTRA_INSTALL+=$(subdir)