Remove spotbugs on automatic build

[henning-gerhardt]

Current execution of spotbugs on automatic build is useless as

• spotbugs messages got lost after build is done
• spotbugs reports more and more issues which not get fixed in time and increasing the log output to an level where the log out is not visible more on GitHub
• spotbugs is configured to only report issues but not break the build. Enabling this breaking on build even for a "high" threshold level would result first in fixing over 100 high level issues reported by spotbugs
• CodeQL integration did at least do the same with a lot better integration into GitHub

Deactivating spotbugs will result in

• (a little bit) faster automatic test execution
• less log output messages