build jobs should not run in MR, and test jobs shoud run before build jobs

I just made my first MR after pipeline migration, and I realized that docker images are build by MR pipelines: https://gitlab.eclipse.org/eclipse/oniro-compliancetoolchain/toolchain/aliens4friends/-/pipelines/12951

This should not happen. Only merged MR should build docker images.

Moreover, test jobs (pytype, unittests) should go before build jobs.