Convert template_preprocess functions in update module

First version done.

There's a duplicate fubction according to phpstan.

I think you forgot to delete update.report.inc and clean up the use statements in update.module and UpdateHooks.

yeah, shouldn't have set this to needs review, didn't expect it to be picked up so quickly, I had to rush at the end as I was running out of time to work on it. And sometimes I forget that you no longer have to set it to needs review for tests to run.

Should be better now.