Enable testing of merge-queues

From [1]

[1]: https://review.trustedfirmware.org/c/next/ci/mbed-tls-job-configs/+/22109

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: Iae654e6967ab06f1c8a76786962e180bcf54b74f
3 files changed