update --times logic

[dsyme]

Based on recent testing

• Update --times option to report wall-clock time, not total user CPU time , since the latter isn't really helpful in multiproc situations, and almost misled us into thinking GC Server was worse, when it actually gives better wallclock performance
• Remove tests for this internal option

@vzarytovskii @KevinRansom Personally I'm happy with just removing the tests for this internal options, I can re-instate them if you like