fix: correct safelyMount check

[SSmallMonster]

What this PR does / why we need it:

• do not output the trailing delimiter when readlink
• split volume path correctly

Special notes for your reviewer:

Does this PR introduce a user-facing change?

[codecov-commenter]

Codecov Report

Merging #1165 (4abcc8b) into main (0f00a8c) will increase coverage by 0.15%.
Report is 4 commits behind head on main.
The diff coverage is 57.14%.

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@@            Coverage Diff             @@
##             main    #1165      +/-   ##
==========================================
+ Coverage   38.83%   38.98%   +0.15%     
==========================================
  Files          25       25              
  Lines        1970     1980      +10     
==========================================
+ Hits          765      772       +7     
- Misses       1103     1106       +3     
  Partials      102      102              

Files	Coverage Δ
...k-manager/handler/localdiskclaim/localdiskclaim.go	69.23% <100.00%> (ø)
pkg/local-disk-manager/filter/filter_disk.go	51.66% <70.00%> (+1.66%)	⬆️
...manager/handler/localdiskvolume/localdiskvolume.go	7.97% <0.00%> (ø)

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