refactor: Create static variables for magic values in deletion vector

[aleksandarskrbic]

Fixes #1442

What changes are proposed in this pull request?

Extract magic numbers from kernel/src/actions/deletion_vector.rs to constants.

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 84.85%. Comparing base (81a8b7d) to head (9a9dca7).

Files with missing lines	Patch %	Lines
kernel/src/actions/deletion_vector.rs	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1446   +/-   ##
=======================================
  Coverage   84.84%   84.85%           
=======================================
  Files         119      119           
  Lines       31031    31031           
  Branches    31031    31031           
=======================================
+ Hits        26329    26332    +3     
+ Misses       3425     3424    -1     
+ Partials     1277     1275    -2     

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