tests: subshell indentation stylefix

tests: subshell indentation stylefix

Format the subshells introduced by the previous patch (Several tests:
cd inside subshell instead of around, 2010-09-06) like so:

	(
		cd subdir &&
		...
	) &&

This is generally easier to read and has the nice side-effect that
this patch will show what commands are used in the subshell, making
it easier to check for lost environment variables and similar
behavior changes.

Cc: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>