[3006.x] Add coverage for `salt/fileclient.py`

[MKLeb]

What does this PR do?

See title

What issues does this PR fix or reference?

Fixes: One file for https://github.com/saltstack/salt/issues/64739

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• [ ] Docs
• [ ] Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• [x] Tests written/updated

Commits signed with GPG?

Yes

[codecov[bot]]

Codecov Report

Merging #65401 (905bdfe) into 3006.x (05541f6) will decrease coverage by 0.01%. Report is 481 commits behind head on 3006.x. The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           3006.x   #65401      +/-   ##
==========================================
- Coverage   62.30%   62.28%   -0.01%     
==========================================
  Files        3218     3218              
  Lines      442586   442583       -3     
  Branches    84722    84722              
==========================================
- Hits       275706   275621      -85     
- Misses     151332   151395      +63     
- Partials    15548    15567      +19     

Flag	Coverage Δ
almalinux-8	58.83% <ø> (-<0.01%)	:arrow_down:
almalinux-9	58.82% <ø> (+0.01%)	:arrow_up:
amazonlinux-2	58.81% <ø> (-<0.01%)	:arrow_down:
archlinux-lts	58.74% <ø> (+0.01%)	:arrow_up:
centos-7	58.88% <ø> (-<0.01%)	:arrow_down:
centosstream-8	58.86% <ø> (-<0.01%)	:arrow_down:
centosstream-9	58.84% <ø> (-<0.01%)	:arrow_down:
debian-10	58.04% <ø> (+0.01%)	:arrow_up:
debian-11	58.01% <ø> (-<0.01%)	:arrow_down:
debian-11-arm64	58.00% <ø> (+0.01%)	:arrow_up:
debian-12	?
debian-12-arm64	57.99% <ø> (+0.01%)	:arrow_up:
fedora-37	58.82% <ø> (-<0.01%)	:arrow_down:
fedora-38	58.76% <ø> (+0.01%)	:arrow_up:
opensuse-15	19.27% <ø> (-38.53%)	:arrow_down:
photonos-3	58.47% <ø> (-0.01%)	:arrow_down:
photonos-4	58.45% <ø> (-<0.01%)	:arrow_down:
photonos-4-arm64	58.27% <ø> (+0.01%)	:arrow_up:
salt	46.42% <ø> (-0.01%)	:arrow_down:
tests	89.85% <ø> (-0.02%)	:arrow_down:
ubuntu-20.04	58.03% <ø> (-<0.01%)	:arrow_down:
ubuntu-20.04-arm64	58.03% <ø> (-<0.01%)	:arrow_down:
ubuntu-22.04	16.09% <ø> (-41.94%)	:arrow_down:
ubuntu-22.04-arm64	58.02% <ø> (-<0.01%)	:arrow_down:
windows-2016	46.71% <ø> (+0.12%)	:arrow_up:
windows-2019	53.23% <ø> (-<0.01%)	:arrow_down:
windows-2022	53.16% <ø> (-0.07%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
salt/fileclient.py	72.61% <ø> (+3.34%)	:arrow_up:

... and 42 files with indirect coverage changes