tracker tests: do not request starting all Tracker services

tracker tests: do not request starting all Tracker services

We don't care about tracker-miner-fs etc. for these tests; all we want
to do is stop any running Tracker stuff. D-Bus service activation will
ensure that we get the necessary services when they're needed, without
starting the unnecessary ones.

(This fixes the Tracker tests on a system without tracker-miner-fs.)

Bug: https://bugzilla.gnome.org/show_bug.cgi?id=697261
Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Reviewed-by: Philip Withnall <philip@tecnocode.co.uk>