Don't use GIT_CONFIG in t5505-remote

For some reason, t5505-remote was setting GIT_CONFIG to .git/config
and exporting it. This should have been no-op, as test framework did
the same for a long time anyway.

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5505-remote.sh

@@ -4,9 +4,6 @@ test_description='git remote porcelain-ish'
 
 . ./test-lib.sh
 
-GIT_CONFIG=.git/config
-export GIT_CONFIG
-
 setup_repository () {
 	mkdir "$1" && (
 	cd "$1" &&