Commitlog replay is given a filename prefix to filter files against, but it
ignores it. As a result we will replay anything in that directory, including
recycled segments, which is wasteful.
Fix by adding a check for the prefix.
Tests: unit (dev), manual test that regular commitlog files are not
filtered.
Message-Id: <20200416174542.133230-1-avi@scylladb.com>