sysbuild: Set CONFIG_SOFTDEVICE on applications when it is enabled

[nordicjm]

The application Kconfigs seem to have been changed, therefore force setting this Kconfig on when it is enabled by sysbuild

[github-actions]

You can find the documentation preview for this PR here.

[anhmolt]

I'm able to fix the failing samples bm_zms_rram and storage_rram by adding SB_CONFIG_SOFTDEVICE_NONE=y to the extra_args: in sample.yaml of these sample variants. But this raises the question weather reintroducing non-SoftDevice boards would be preferable.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[github-actions]

This pull request has been marked as stale because it has been open (more than) 30 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 7 days. Note, that you can always re-open a closed pull request at any time.