Fix the flakey TestSpaceQuotas

branch-2.2 shows this tests frequent failure in the precommit jobs (808,809). Also master branch has this test on it's flakey list. Looks like bour TestSpaceQuotas is pretty overloaded because of all the sleeps(of 5 seconds) in the write-until-policy-violated attempts. Also to verify the violation, our numer of retries is 10 and each time we sleep 5 secs before checking again. So we could often cross the 13 mins limit and get timeout eventually leading to appearance of TestSpaceQuotas in the flakey list.

An e.g. here: https://builds.apache.org/view/H-L/view/HBase/job/HBase-adhoc-run-tests/27/

Let's refactor & break TestSpaceQuotas into more tests so that none of the tests cross the 13 min limit as we cannot make this into an IntegrationTest.