Fix invalid if condition in Github Actions

[leonard84]

The value of an if: entry is already an expression block, so usage of ${{ }} is not necessary, except in one rare case (https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/using-conditions-to-control-job-execution).
However, it is easy to accidentally create an invalid condition:
${{ matrix.java-build-tool }} == 'maven' will always evaluate to true, due to a quirk of how nested expression context are evaluated.
Correct is either

• ${{ matrix.java-build-tool == 'maven' }}
• matrix.java-build-tool == 'maven'

I've choosen to use the latter as it is simpler.
I've also cleaned up unnecessary use of ${{ }} in other if blocks.

[CLAassistant]

All committers have signed the CLA.

[leonard84]

To see the bug in action, see both

• https://github.com/jhipster/jhipster-lite/actions/runs/10985776285/job/30498344252#step:16:18
• https://github.com/jhipster/jhipster-lite/actions/runs/10985776285/job/30498344252#step:18:22

If the condition were working as intended, only one of the cache actions should have been active, and the other would have been skipped.

[murdos]

Thanks @leonard84 for the fix and the explanation.
Much appreciated!