Revert "osd/PGLog.cc: Trim duplicates by number of entries"

Revert "osd/PGLog.cc: Trim duplicates by number of entries"

This reverts commit 7cc1b29f2b7b7feee127f1dbbef947799e56f38b.
which is the in-OSD part of the fix for accumulation of `dup`
entries in a PG Log. Brainstorming it has brought questions
on the OSD's behaviour during an upgrade if there are tons of
dups in the log. What must be double-checked before bringing
it back is ensuring we chunk the deletions properly to not
impose OOMs / stalls in, to exemplify, RocksDB.

The backport ticket is: https://tracker.ceph.com/issues/55990

Signed-off-by: Radoslaw Zarzynski <rzarzyns@redhat.com>