fix(git-node): remove duplicated code in prepare_release.js

[aduh95]

As I was working on security release, I noticed the --release-date flag was ignored. I figured, rather than trying to fix all the flags, it'd be better to remove the duplication and re-use the well tested regular release path.

Security releases preparation follow the same steps as regular releases, having duplicated steps is only cumbersome AFAICT.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.93%. Comparing base (5034b4f) to head (6541519).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1047   +/-   ##
=======================================
  Coverage   80.93%   80.93%           
=======================================
  Files          39       39           
  Lines        4841     4841           
=======================================
  Hits         3918     3918           
  Misses        923      923           

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