test: add isolated prune case (to test-obsolete-bundle-strip.t) This adds a test where the prune marker is not related to any other obsmarkers.

test-obsolete-bundle-strip: add a complex split and fold case This is a more complex case that checks the logic used when split and fold gets into play.

test-obsolete-bundle-strip: add cases with prune on missing revs Same as the previously added case, but the prune is no longer known locally. This will mostly matter for the strip testing. Introducing the test early will help clarify patches related to strip.