Tie-break suggestions from phrase suggester by term

If the score for two suggestions is the same, we now tie break by term; earlier terms (aaa) sort before later terms (zzz).

Closes #5978
[TEST] Stabelize MoreLikeThisActionTests

The `testCompareMoreLikeThisDSLWithAPI` test compares results from query
and API which might query different shards. Those shares might use
different doc IDs internally to disambiguate. This commit resorts the
results and compares them after stable disambiguation.
[TEST] Beef up MoreLikeThisActionTests#testCompareMoreLikeThisDSLWithAPI