Implement better trim functionality

[AbyelT]

The current trim() of PersistentStorage is implemented as a temporary solution. The only function that can remove elements from commitlog, truncate(offset) does not remove the first element as it only deletes entries after offset. This is still an open issue at Commitlog

Trim() works by getting the entries that should remain after trimming and then removing the commitlog through std::fs, It then recreates the commitlog and appends the entries. This operation is costly in performance and there could be better ways to trim the commitlog.

Mentioned by @haraldng in https://github.com/haraldng/omnipaxos/pull/48#discussion_r929044356_