Set `split_by_inds`, `test_labels`, and `validation_labels` to default (GUI)

[roomrys]

Description

1053 allowed some unseen parameter to be used in GUI training when a trained model was used as a template. While certain parameters were set to defaults, others were controversially left to the values used in the trained model.

This PR sets more parameters to defaults, namely

• labels.split_by_inds
• labels.validation_labels
• labels.test_labels

which aims to ensure training is run on the labels in the current project. #1324 attempted to give the GUI user a bit more control, but ultimately it was decided that #1324 might cause more confusion than clarity.

Types of changes

• [x] Bugfix
• [ ] New feature
• [ ] Refactor / Code style update (no logical changes)
• [ ] Build / CI changes
• [ ] Documentation Update
• [ ] Other (explain)

Does this address any currently open issues?

• 1291

Outside contributors checklist

• [ ] Review the guidelines for contributing to this repository
• [ ] Read and sign the CLA and add yourself to the authors list
• [ ] Make sure you are making a pull request against the develop branch (not main). Also you should start your branch off develop
• [ ] Add tests that prove your fix is effective or that your feature works
• [ ] Add necessary documentation (if appropriate)

Thank you for contributing to SLEAP!

:heart:

[codecov[bot]]

Codecov Report

Merging #1331 (5300223) into develop (4525462) will decrease coverage by 0.01%. The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #1331      +/-   ##
===========================================
- Coverage    72.66%   72.66%   -0.01%     
===========================================
  Files          133      133              
  Lines        23675    23678       +3     
===========================================
+ Hits         17204    17206       +2     
- Misses        6471     6472       +1     

Impacted Files	Coverage Δ
sleap/gui/learning/dialog.py	67.67% <100.00%> (-0.01%)	:arrow_down:

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