Remove Vault support entirely from WildFly Core

Users of WildFly can use the Elytron credential store for the secure storage of credentials, support has also been added for encrypted expressions for values encrypted using a secret key contained within the credential store.

It is now time to completely remove the deprecated vault support.

Other tasks will include reviewing use across the testsuite, any use within quickstarts and across our documentation.

As I submit the PRs for removal I also plan to publish a blog stating the removal is in place and call out the alternatives with the credential store.