[FTS] moss store files are not deleted after compaction

While looking at the recent moss store compaction performance results with Alex Gyryk, the following issue was observed..

 total 33G

rw------. 1 couchbase couchbase  13K Mar 27 11:26 data-0000000000000001.moss

rw------. 1 couchbase couchbase  25M Mar 27 11:26 data-000000000000000b.moss

rw------. 1 couchbase couchbase 1.7G Mar 27 11:28 data-000000000000001b.moss

rw------. 1 couchbase couchbase 2.1G Mar 27 11:28 data-000000000000001c.moss

rw------. 1 couchbase couchbase 2.5G Mar 27 11:29 data-000000000000001d.moss

rw------. 1 couchbase couchbase 3.0G Mar 27 11:30 data-000000000000001e.moss

rw------. 1 couchbase couchbase 3.6G Mar 27 11:30 data-000000000000001f.moss

rw------. 1 couchbase couchbase 4.2G Mar 27 11:31 data-0000000000000020.moss

rw------. 1 couchbase couchbase 5.0G Mar 27 11:32 data-0000000000000021.moss

rw------. 1 couchbase couchbase 6.0G Mar 27 11:34 data-0000000000000022.moss

There were 11 older files which were not cleaned up since the test began. The last file "22.moss" kept increasing in size and then soon enough "23.moss" was being created.

rw------. 1 couchbase couchbase 5.2G Mar 27 11:34 data-0000000000000023.moss

After 23.moss is created 22.moss continues to remain. This causes the system to quickly run out of space.

It appears that this issue is only seen when the compaction percentage is set to a non-zero value.