qtest: bump migration-test timeout to 8 minutes

qtest: bump migration-test timeout to 8 minutes

The migration test should take between 1 min 30 and 2 mins on reasonably
modern hardware. The test is not especially compute bound, rather its
running time is dominated by the guest RAM size relative to the
bandwidth cap, which forces each iteration to take at least 30 seconds.
None the less under high load conditions with multiple QEMU processes
spawned and competing with other parallel tests, the worst case running
time might be somewhat extended. Bumping the timeout to 8 minutes gives
us good headroom, while still catching stuck tests relatively quickly.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20230717182859.707658-3-berrange@redhat.com>
[thuth: Bump timeout to 8 minutes to make it work on very loaded systems, too]
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20231215070357.10888-3-thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>