BUG: Fix ellipse translation in app.get_subsets()

[pllim]

Description

This pull request is to fix #2241 quickly without having to wait for upstream.

Change log entry

• Is a change log needed? If yes, is it added to CHANGES.rst? If you want to avoid merge conflicts,
  list the proposed change log here for review and add to CHANGES.rst before merge. If no, maintainer
  should add a no-changelog-entry-needed label.

Checklist for package maintainer(s)

This checklist is meant to remind the package maintainer(s) who will review this pull request of some common things to look for. This list is not exhaustive.

• Are two approvals required? Branch protection rule does not check for the second approval. If a second approval is not necessary, please apply the trivial label.
• Do the proposed changes actually accomplish desired goals? Also manually run the affected example notebooks, if necessary.
• Do the proposed changes follow the STScI Style Guides?
• Are tests added/updated as required? If so, do they follow the STScI Style Guides?
• Are docs added/updated as required? If so, do they follow the STScI Style Guides?
• Did the CI pass? If not, are the failures related?
• Is a milestone set? Set this to bugfix milestone if this is a bug fix and needs to be released ASAP; otherwise, set this to the next major release milestone.
• After merge, any internal documentations need updating (e.g., JIRA, Innerspace)?

[pllim]

Ugh... RTD failure is unrelated. Might be my fault still. I'll have to investigate separately.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.02 ⚠️

Comparison is base (62948ba) 91.64% compared to head (f530f52) 91.63%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2244      +/-   ##
==========================================
- Coverage   91.64%   91.63%   -0.02%     
==========================================
  Files         148      148              
  Lines       16538    16538              
==========================================
- Hits        15157    15154       -3     
- Misses       1381     1384       +3     

Impacted Files	Coverage Δ
jdaviz/app.py	93.15% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[duytnguyendtn]

Fixes my issue, thanks! Not sure what you want to do about that doc failure

[pllim]

Doc failure is already fixed upstream.