[workaround] install SDP requirements in the test environment, because requirements-sdp.txt is ignored

[zacharyburnett]

This PR applies a workaround for the issue where the delivered SDP dependencies are not actually drawn from requirements-sdp.txt but instead from the Jenkinsfile test environment

Checklist

• added entry in CHANGES.rst under the corresponding subsection
• updated relevant tests
• updated relevant documentation
• updated relevant milestone(s)
• added relevant label(s)
• ran regression tests, post a link to the Jenkins job below. How to run regression tests on a PR

[zacharyburnett]

regtests running at https://plwishmaster.stsci.edu:8081/blue/organizations/jenkins/RT%2FRoman-Developers-Pull-Requests/detail/Roman-Developers-Pull-Requests/503/pipeline/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (9b14c88) 70.94% compared to head (222cb68) 70.94%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1033   +/-   ##
=======================================
  Coverage   70.94%   70.94%           
=======================================
  Files         105      105           
  Lines        6979     6979           
=======================================
  Hits         4951     4951           
  Misses       2028     2028           

Flag	Coverage Δ		*Carryforward flag
nightly	63.06% <ø> (ø)		Carriedforward from 9b14c88

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