Simplify 'eos evict' output message

Problem

The output of the eos evict command can be slightly confusing, depending on the input arguments.

Example:

removed all disk replicas for 1/1 files; reduced evict counter for 0/1 files

This means:

• 1 file had all its disk replicas removed (eos evict command can accept a list of files).
• 0 files had its evict counters reduced (not the case here, since the only file passed as a paremeter was evicted).

The actually meaning of this message can be confusing.

Code:

• https://gitlab.cern.ch/dss/eos/-/blob/master/mgm/proc/admin/EvictCmd.cc#L394-L411

Proposed solution

I propose the following changes to the eos evict ouptut message (numbers used as an example):

• If the optional arguments --fsid <fsid> and --ignore-evict-counter are passed:
  • "found and removed the fsid=123 disk replica for 5 files"
  • If --ignore-removal-on-fst was also passed append:
    • "(namespace only)"
• If only the optional argument --ignore-evict-counter is passed:
  • "removed all disk replicas for 5 files"
• Otherwise:
  • If all files got it's evict counter reduced to zero (meaning all got evicted):
    • "reduced evict counter for 5 files; removed all disk replicas for 5/5 files"
  • If not all files got its evict counter reduced to zero:
    • "reduced evict counter for 5 files; removed all disk replicas for 3/5 files"