[SPARK-10378][SQL][Test] Remove HashJoinCompatibilitySuite.

[rxin]

They don't bring much value since we now have better unit test coverage for hash joins. This will also help reduce the test time.

[vanzin]

I have a different approach in #8437 (which doesn't get rid of the tests here).

[rxin]

@vanzin we can have both, can't we? I don't think HashJoinCompatibilitySuite is testing much here, given we added more tests for hash joins. In general, operator tests should be done not at the end-to-end level. The Hive tests are great in the beginning to beef up our test coverage with little effort, but their values are decreasing everyday.

[vanzin]

Sure, I was just wondering because the reasoning on the bug is "to make the tests run faster" and not "the test doesn't really add value".

[SparkQA]

Test build #41843 has finished for PR 8542 at commit 46b7112.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.