Remove unneeded function_exists checks

[dkotter]

What?

Remove unneeded function_exists checks

Why?

As mentioned here, we have some function_exists checks that aren't technically needed since the functions we check for are in versions of WordPress that match or exceed our minimum (6.9 and 7.0).

How?

For any core WordPress functions that we know are always available in WordPress 7.0 (our minimum) remove function_exists checks

Use of AI Tools

None

Testing Instructions

Not a lot needed here other than ensuring tests pass. Could also test the Abilities Explorer experiment to ensure it still works as expected

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: dkotter <dkotter@git.wordpress.org>
Co-authored-by: jeffpaul <jeffpaul@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.89%. Comparing base (aa6409b) to head (b63f9d7).
⚠️ Report is 4 commits behind head on develop.

Files with missing lines	Patch %	Lines
includes/bootstrap.php	0.00%	1 Missing ⚠️
includes/helpers.php	0.00%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop     #378      +/-   ##
=============================================
+ Coverage      63.81%   63.89%   +0.08%     
+ Complexity       684      680       -4     
=============================================
  Files             49       49              
  Lines           3529     3518      -11     
=============================================
- Hits            2252     2248       -4     
+ Misses          1277     1270       -7     

Flag	Coverage Δ
unit	63.89% <50.00%> (+0.08%)	⬆️

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[jeffpaul]

Tested via Playground, OAI, and Title Gen worked as expected