MB-25869: Improve readability of 'test_vbucket_compact'
MB-25869: Improve readability of 'test_vbucket_compact'

This commit improves the readability of the legacy test case
'test_vbucket_compact' and also upgrades it to our current
coding guidelines.

Change-Id: I814d5cc47a1105d01c68cda74b5caa7ed7548edc
Reviewed-on: http://review.couchbase.org/84321
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine