[TEST] Pick random version from backwards directory

The upgrade tests required to specify the lower and the upper version
that it should run against. This commit adds support for random picks
if either the lower or the upper or both are not specified.
Test: finish all merges before test returns to side step 'Delete Index failed - not acked' failure
[TEST] randomize byte size and thread count in breaker tests
Packaging: Dont remove ancestors on deb removal

The used -p option could result in accidentally deleting more directories
than /var/lib/elasticsearch - so this option was removed

Note: This only happens if the directories are empty, but still isnt needed.

Relates #5770