Migrate TPConverter unit tests to ComponentAccumulator

The main purpose of this merge request is to migrate all remaning TPConverter unit tests which were previously run using athena+jobOptions to use ComponentAccumulator-based python scripts. In order to get the output to match the reference files produced with the old-style configuration the MessageSvc configuration had to be tweaked.

In addition the log file diff in post_tpcnvtest.sh was updated in a similar way to the update of post.sh in !35801 (merged).
Prior to this change log file diffs in unit tests compared the reference file to the current output, rather than the other way around, so that lines in the log removed due to local changes are marked with a + in the diff output and lines added to the log are marked with a -.
This change switches the order of comparison with the aim of making the output more intuitive.