Fix FIFO Compaction with TTL tests
Fix FIFO Compaction with TTL tests

Summary:
- FIFOCompactionWithTTLTest was flaky when run in parallel earlier, and hence it was disabled. Fixed it now.
- Also, faking sleep now instead of really sleeping to make tests more realistic by using TTLs like 1 hour and 1 day.
Closes https://github.com/facebook/rocksdb/pull/2650

Differential Revision: D5506038

Pulled By: sagar0

fbshipit-source-id: deb429a527f045e3e2c5138b547c3e8ac8586aa2

SunguckLee/RocksDB,Andymic/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,Andymic/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,Andymic/rocksdb,bbiao/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,bbiao/rocksdb,Andymic/rocksdb