fix abs_deriv edge effects

[braingram]

Resolves JP-nnnn

Regression tests running at: https://plwishmaster.stsci.edu:8081/job/RT/job/JWST-Developers-Pull-Requests/1595/

Closes #

This PR addresses ...

Checklist for PR authors (skip items if you don't have permissions or they are not applicable)

• added entry in CHANGES.rst within the relevant release section
• updated or added relevant tests
• updated relevant documentation
• added relevant milestone
• added relevant label(s)
• ran regression tests, post a link to the Jenkins job below.
  How to run regression tests on a PR
• All comments are resolved
• Make sure the JIRA ticket is resolved properly

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.56%. Comparing base (69a10bc) to head (8ff0e44).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8635      +/-   ##
==========================================
+ Coverage   59.52%   59.56%   +0.04%     
==========================================
  Files         391      391              
  Lines       39321    39280      -41     
==========================================
- Hits        23405    23397       -8     
+ Misses      15916    15883      -33     

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