Cleanup: add/remove apostrophes; remove backtick

[mbrukman]

What does this PR do?

Add apostrophes to "it's" where the indended use is "it is" instead of "its" (possessive) and vice versa, remove the apostrophe where the intended use is possessive.

Remove unnecessary backtick within a word (typo).

Checklist

• [x] This PR fixes a minor issue (e.g.: typo or small bug) or improves the docs (you can dismiss the other checks if that's the case).
• [ ] This change is discussed in a Github issue/ discussion (please add a link).
• [ ] The documentation and docstrings adhere to the documentation guidelines.
• [ ] This change includes necessary high-coverage tests. (No quality testing = no merge!)