Fixes typos in test class names, test method names and test variable names.

Comment From: sbrannen

This has been merged into 5.3.x and main.

Thanks for all of your effort recently in cleaning up typos! 👍

Comment From: marcwrobel

You are welcome, it was the opportunity to contribute a little bit to this project I used for so many years.

Only a few more PR (#28819, #28821, #28822) and it's done.