rgw/d4n: this commit squashes the following commits related to LFUDA Policy.

rgw/d4n: this commit squashes the following commits related to LFUDA Policy.

rgw/d4n: Make minor updates, improve `LFUDAPolicy::erase` method, and
fix `localWeight` policy sets
rgw/d4n: Update `LFUDA::find_victim` method, add locks in policy code,
and remove setting of attrs in filter's `put_async` calls
d4n/policy: Update logic for minimum average weight calculation
d4n/policy: Remove iteration in `eviction`

Signed-off-by: Samarah <samarah.uriarte@ibm.com>