crash_test: disable periodic compaction in FIFO compaction. (#5993)

Summary:
A recent commit make periodic compaction option valid in FIFO, which means TTL. But we fail to disable it in crash test, causing assert failure. Fix it by having it disabled.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5993

Test Plan: Restart "make crash_test" many times and make sure --periodic_compaction_seconds=0 is always the case when --compaction_style=2

Differential Revision: D18263223

fbshipit-source-id: c91a802017d83ae89ac43827d1b0012861933814

tools/db_crashtest.py

@@ -175,6 +175,7 @@ def finalize_and_sanitize(src_params):
         # Disable compaction TTL in FIFO compaction, because right
         # now assertion failures are triggered.
         dest_params["compaction_ttl"] = 0
+        dest_params["periodic_compaction_seconds"] = 0
     if dest_params["partition_filters"] == 1:
         if dest_params["index_type"] != 2:
             dest_params["partition_filters"] = 0