GHA: enclose `if` expressions in `${{ }}` where missing

GHA: enclose `if` expressions in `${{ }}` where missing

Enclosing expressions in `${{ }}` is optional, but sometimes required.
It seems more straighforward to use it always rather than decide on
a case-by-case basis. Before this patch 71 `if`s were enclosed and 49
were not. Enclosing these makes it easy to grep and recognize these
whereever used.

https://docs.github.com/actions/writing-workflows/choosing-when-your-workflow-runs/using-conditions-to-control-job-execution

Closes #17550