Learning Mode - Do not filter templates for query slugs if it is indexing.

[dadish]

Fixes #5311

Changes proposed in this Pull Request

• Checks if the query slugs are for indexing before filtering the templates.

Testing instructions

Without a bock-based theme:

1. Activate Twenty Twenty-One theme (not block-based theme).
2. Go to WP Admin > Appearance > Editor.
3. Confirm the FSE works and you can customize the Learning Mode template.

With a bock-based theme, but with the theme styles disabled:

1. Activate Twenty Twenty-Two theme (block-based theme).
2. Go to WP Admin > Sensei LMS > Settings > Courses.
3. Disable the option "Enable theme styles".
4. Go to WP Admin > Appearance > Editor > Browse all templates (this option appears when expanding the "Home >" in the top bar).
5. Click on "Lesson (Learning Mode)".
6. Confirm the FSE works and you can customize the Learning Mode template.

For Post Type

• Edit regular post.
• Confirm that it does not have "Learning Mode (Lesson)" template for FSE editing.

[codecov]

Codecov Report

Merging #5460 (c6af0b3) into trunk (16a2937) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##              trunk    #5460      +/-   ##
============================================
- Coverage     44.54%   44.53%   -0.01%     
- Complexity     8749     8753       +4     
============================================
  Files           412      412              
  Lines         31166    31166              
  Branches        234      234              
============================================
- Hits          13882    13881       -1     
- Misses        17111    17112       +1     
  Partials        173      173              

Impacted Files	Coverage Δ
...urse-theme/class-sensei-course-theme-templates.php	0.00% <0.00%> (ø)
includes/class-sensei-quiz.php	59.04% <0.00%> (-0.14%)	⬇️

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[yscik]

Works good! I added another check, there were warnings in the other filter when using a block theme.