jobs/osmocom-api: run inside docker

Run the osmocom-api job inside docker, so all depends are available
(fixes that it currently fails because liburing isn't available for
libosmocore).

Use the contrib/known_hosts file, instead of writing an own copy during
the job.

Change-Id: I6e831c71c4c88772c3e4232fcb1a9e2c1c73d997
2 files changed