Make homedir easier to test

What does this MR do?

Make homedir easier to test

This is to deflake the tests re. the homedir helper. It also backfills tests for other methods.

Why was this MR needed?

To deflake some tests and backfill some ohters

What's the best way to test this MR?

go test -v -count=1000 -failfast ./helpers/homedir/

What are the relevant issue numbers?

closes: #38314 (closed)