Gracefully handle builder instantiation errors when building findings

The following discussion from !136138 (merged) should be addressed:

• @brytannia started a discussion: (+1 comment)

  the .for_purl_type! will raise an error if purl_type not of dependency_scanning type. We have error handling only in execute method. So if the error is actually raised here we should bubble up to the execute and will skip every other affected_component in finding_maps. I see there is a test for such case, but is it possible to test as well if we not skipping finding building for other components?

  Is the purl_type of each affected_component is the same, maybe we can "build" builder once?