Switch to `String#isBlank` and `String#strip`

## Overview

Since we now have a Java 17 baseline, we can make use of `String#isBlank` and `String#strip` (instead of `String#trim`) in various places throughout the code base.

I don't foresee any issues regarding "stripping" vs. "trimming", but if users report issues we can then revisit our use of `strip()` in particular scenarios.

## Related Issues

- #4246 