ci-package-builder: Wait for the right build to begin

Sometimes we call osc remotebuildlog before the new build is scheduled and OBS happily gives us the log for the past build.

In these cases the CI log will show the dump of the old build and then spin waiting for the results. Luckily we ask for the results in a specific way, so we only return with the results of the revision we just uploaded.

To avoid showing an irrelevant obsolete log instead of the current one, look for the srcmd5 included in the log and spin until it matches.

Task: T6873