ci: Removed use_new_release input from prepare release workflow

[svetlanabrennan]

Description

We no longer need to use use_new_release input variable in the prepare release workflow since that will be the only option. Also added changelog_file input since it was missing.

Related Issues

Related to: newrelic/node-newrelic#2124
Partially fixes: newrelic/node-newrelic#2113

ToDo

• Remove USE_NEW_RELEASE from github action variables

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.98%. Comparing base (9d716ba) to head (dc003ab).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #293   +/-   ##
=======================================
  Coverage   98.98%   98.98%           
=======================================
  Files           7        7           
  Lines         891      891           
=======================================
  Hits          882      882           
  Misses          9        9           

Flag	Coverage Δ
integration-tests-16.x	93.93% <ø> (?)
integration-tests-18.x	93.93% <ø> (ø)
integration-tests-20.x	93.93% <ø> (?)
unit-tests-16.x	59.70% <ø> (?)
unit-tests-18.x	59.70% <ø> (ø)
unit-tests-20.x	59.70% <ø> (?)
versioned-tests-16.x	95.84% <ø> (ø)
versioned-tests-18.x	95.84% <ø> (ø)
versioned-tests-20.x	95.84% <ø> (ø)

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