fix(maven): ignore generic build failure banners in log handler (#6870)

[Ankitraj-sharma]

Fixes #6870

Motivation

In newer runner images (and modern Maven 3.9+), Maven outputs the failure summary banner [ERROR] BUILD FAILURE and divider lines [ERROR] ------------------------------------------------------------------------ with log level ERROR rather than INFO.

Because pkg/util/command.go's scan records the first non-empty error message returned by LogHandler, the generic banner "BUILD FAILURE" was permanently recorded as the command's error message, shadowing the actual informative failure reason that follows (e.g. "The goal you specified requires a project to execute but there is no POM in this directory"). This caused TestRunAndLogErrorMvn to fail with:

Error "BUILD FAILURE: exit status 1" does not contain "The goal you specified requires a project to execute but there is no POM in this directory"

It also resulted in Maven failures in the builder (pkg/builder/jib.go) reporting only "BUILD FAILURE: exit status 1" without the actionable error reason.

Modifications

• Updated LogHandler in pkg/util/maven/maven_log.go to ignore non-diagnostic Maven banners (BUILD FAILURE, BUILD ERROR), separator lines (---...), and execution summary timings (Total time:, Finished at:) so that the actual root cause message is returned to the caller.
• Handled both ERROR and FATAL levels consistently with normalizeLog.
• In pkg/util/maven/maven_log_test.go:
  • Added a skip check in TestRunAndLogErrorMvn if mvn is not present in PATH.
  • Added unit test TestLogHandler verifying banner and separator filtering.
  • Added unit test TestLogHandlerMavenFailureSequence verifying that the informative error is correctly extracted from the Maven 3.9+ failure stream.

[squakez]

I think we can make it simpler that this. We can just remove the "ErrorContains" condition and avoid checking the reason. In the future we will probably refactor this part, so, no need to put more logic there.

[squakez]

Check failure happens in build main (used for coverage diff).