Generate a locale-agnostic initdb template

Fixup for 252dcb3239.

Without this, the "template" data directory created in the initial test
steps uses a non-C locale, upsetting numerous tests that rely on parsing
English error messages.

Discussion: https://postgr.es/m/CAFj8pRB=XVWC0orWu0FbjrmyOpAMLqJiau80YyQOYQPfMj8Xxw@mail.gmail.com

meson.build

@@ -3107,7 +3107,7 @@ sys.exit(sp.returncode)
 ''',
        test_initdb_template,
        temp_install_bindir / 'initdb',
-       '-A', 'trust', '-N', '--no-instructions'
+       '-A', 'trust', '-N', '--no-instructions', '--no-locale'
      ],
      priority: setup_tests_priority - 1,
      timeout: 300,

src/Makefile.global.in

@@ -425,7 +425,7 @@ ifeq ($(MAKELEVEL),0)
 	$(MAKE) -C '$(top_builddir)' DESTDIR='$(abs_top_builddir)'/tmp_install install >'$(abs_top_builddir)'/tmp_install/log/install.log 2>&1
 	$(MAKE) -j1 $(if $(CHECKPREP_TOP),-C $(CHECKPREP_TOP),) checkprep >>'$(abs_top_builddir)'/tmp_install/log/install.log 2>&1
 
-	$(with_temp_install) initdb -A trust -N --no-instructions '$(abs_top_builddir)'/tmp_install/initdb-template >>'$(abs_top_builddir)'/tmp_install/log/initdb-template.log 2>&1
+	$(with_temp_install) initdb -A trust -N --no-instructions --no-locale '$(abs_top_builddir)'/tmp_install/initdb-template >>'$(abs_top_builddir)'/tmp_install/log/initdb-template.log 2>&1
 endif
 endif
 endif