Fix race condition

After staging an APEX, wait for the compilation job to be scheduled
before forcing it to run. The job is scheduled asynchronously to us,
so we can't assume it's already happened.

Test: atest CompOsSigningHostTest
Bug: 217851780
Change-Id: I7bf93a98007ae53dba3ce7b35ee8332946d50eb1
1 file changed