Revert "test: use gpgconf --create-socketdir if available"

This reverts commit e7b88e8b0a.

It turns out that this does not work well in environments without a
running systemd (or some other provider of /run/user)

test/test-lib.sh

@@ -229,19 +229,10 @@ test_fixed=0
 test_broken=0
 test_success=0
 
-
-_shutdown_gpg_agent () {
-    if [ ${NOTMUCH_HAVE_GPGCONF_SOCKETDIR} = 1 ]; then
-	gpgconf --kill gpg-agent
-	gpgconf --remove-socketdir
-    fi
-}
-
 _exit_common () {
 	code=$?
 	trap - EXIT
 	set +ex
-	_shutdown_gpg_agent
 	rm -rf "$TEST_TMPDIR"
 }
 
@@ -1285,11 +1276,6 @@ test_init_ () {
 
 . ./test-lib-common.sh || exit 1
 
-# we need the setting of GNUPGHOME in test-lib-common.sh
-if [ ${NOTMUCH_HAVE_GPGCONF_SOCKETDIR} = 1 ]; then
-    gpgconf --create-socketdir
-fi
-
 emacs_generate_script