Inconsistent handling of deprecated dark variants examples

[carlosmintfan]

Prerequisites

• I have searched for duplicate or closed issues
• I have validated any HTML to avoid common problems
• I have read the contributing guidelines

Describe the issue

I’ve detected that the docs are providing the example code for the dark variants in two different, inconsistent ways: Some components still show the old code after the deprecated warning while others show the warning and then directly the new code using the color modes feature. I suggest showing both for maximum clarity and ease of copying and clearly state which one is deprecated and which one is recommended.
Note that the "deprecated" badge at the examples showing the new (not deprecated!) code could be a bit misleading or "making sad" without reading the callout.

Reduced test cases

https://getbootstrap.com/docs/5.3/components/dropdowns/#dark-dropdowns using the old variant class
https://getbootstrap.com/docs/5.3/components/navbar/#color-schemes using new code
https://getbootstrap.com/docs/5.3/components/navbar/#color-schemes using new code
And possibly more…

What operating system(s) are you seeing the problem on?

Windows, macOS, Android, iOS, Linux

What browser(s) are you seeing the problem on?

Chrome, Safari, Firefox, Microsoft Edge, Opera

What version of Bootstrap are you using?

5.3.3

[julien-deramond]

Thanks for reporting this issue @carlosmintfan
There was no issue in the backlog, but #39291 already existed trying to tackle it
So let's keep your issue as a reference, and link #39291 to it :)