common: Double the timeout for common/telepathy-gabble.yaml again

It seems that importing pyopenssl now takes longer than it did before,
which affects each iteration of the telepathy-gabble tests, and makes
them take a little more than the 30 minute timeout on an i.MX6.

Double the timeout again to prevent test failures even when the tests
are making progress.

Signed-off-by: Philip Withnall <philip.withnall@collabora.co.uk>
Reviewed-by: Luis Araujo <luis.araujo@collabora.com>
Differential Revision: https://phabricator.apertis.org/D4122