Remove an assertion in FlushAfterIntraL0CompactionCheckConsistencyFail (#7003)

Summary:
FlushAfterIntraL0CompactionCheckConsistencyFail is flakey. It sometimes fails with:

db/db_compaction_test.cc:5186: Failure
Expected equality of these values:
  10
  NumTableFilesAtLevel(0)
    Which is: 3

I don't see a clear reason why the assertion would always be true. The necessarily of the assertion is not clear either. Remove it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7003

Test Plan: See the test still builds.

Reviewed By: riversand963

Differential Revision: D22129753

fbshipit-source-id: 42f0bb05e32b369e8d726bfd3e35c29cf52fe008

db/db_compaction_test.cc

@@ -5183,7 +5183,6 @@ TEST_P(DBCompactionTestWithParam,
   // Put one key, to make biggest log sequence number in this memtable is bigger
   // than sst which would be ingested in next step.
   ASSERT_OK(Put(Key(2), "b"));
-  ASSERT_EQ(10, NumTableFilesAtLevel(0));
   dbfull()->TEST_WaitForCompact();
   ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->DisableProcessing();
   std::vector<std::vector<FileMetaData>> level_to_files;