t5619: GETTEXT_POISON fix

In cf8f6ce02a (clone: delay picking a transport until after
get_repo_path(), 2023-01-24), we backported a patch onto v2.30.* that
was originally based on a much newer version. The v2.30.* release train
still has the GETTEXT_POISON CI job, though, and hence needs
`test_i18n*` in its tests.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

t/t5619-clone-local-ambiguous-transport.sh

@@ -64,7 +64,7 @@ test_expect_success 'ambiguous transport does not lead to arbitrary file-inclusi
 	#
 	# This works for now, and if we ever fix the URL detection, it
 	# is OK to change this to detect the transport error.
-	grep "protocol .* is not supported" err
+	test_i18ngrep "protocol .* is not supported" err
 '
 
 test_done