The DNS feature requires a restart, so flag it

[zeroSteiner]

This updates the DNS feature definition in the feature manager to:

1. Mark that it requires the framework to be restarted in order for it to be activated (because the resolver attribute on the framework instance needs to be set)
2. Rename it from DNS_FEATURE to DNS because the FEATURE suffix is redundant in this case and inconsistent with the other names

Fixes #18948

Verification

• Follow the steps from DNS feature stops working when trying to use it before enabling the feature #18948 and see that the issue is now fixed

Demo

[cdelafuente-r7]

Thank you @zeroSteiner for fixing this, I just updated the wording as we discussed in this commit

[cdelafuente-r7]

Release Notes

This updates the DNS feature to notify the user a restart is required when the feature is enabled or disabled.