JP-3248: MIRI Subarrays 390 Hz EMI bug fix

[penaguerrero]

Resolves JP-3248

Closes #

This PR addresses emicorr crashing with readpatt values other than FASTR1 or SLOWR1.

Checklist for maintainers

• 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
• Make sure the JIRA ticket is resolved properly

[penaguerrero]

running reg tests at: https://plwishmaster.stsci.edu:8081/job/RT/job/JWST-Developers-Pull-Requests/1107/

[codecov]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (39d0e3f) 75.24% compared to head (bb8dc0c) 75.24%.

Files	Patch %	Lines
jwst/emicorr/emicorr.py	77.77%	4 Missing ⚠️
jwst/emicorr/emicorr_step.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8147   +/-   ##
=======================================
  Coverage   75.24%   75.24%           
=======================================
  Files         470      470           
  Lines       38421    38430    +9     
=======================================
+ Hits        28909    28916    +7     
- Misses       9512     9514    +2     

Flag	Coverage Δ		*Carryforward flag
nightly	77.37% <ø> (ø)		Carriedforward from 39d0e3f

*This pull request uses carry forward flags. Click here to find out more.

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[hbushouse]

Code updates and CI test results look good. Progress so far on regtests also looks good. Will reserve final approval until regtests finish.

[hbushouse]

Regtest result is clean.