Move elytron management security tests from full to core

Since until recently the elytron subsystem wasn't part of the core feature pack, a lot of integration tests of its use ended up in the WildFly full testsuite instead of in core. This task is to get tests that are only testing core functionality moved into the core testsuite. Because that's the right thing to do, but also because it's useful in practice by eliminating a cause for messy coordinated changes to core and full such that code changes in core can be tested.

Corresponding Wildfly JIRA: https://issues.jboss.org/browse/WFLY-8723

There are a number of aspects to this, for which I'll create subtasks.

Following is an initial list of tests that should be moved. This is meant to be a living list, with things added as they are noticed. So anyone should feel free to edit this JIRA description to add things to the list.

org.jboss.as.test.integration.security.perimeter.* [2]
org.jboss.as.test.manualmode.mgmt.elytron.HttpMgmtInterfaceElytronAuthenticationTestCase
org.jboss.as.test.integration.domain.AbstractSlaveHCAuthenticationTestCase and subclasses.[1]
org.jboss.as.test.integration.security.credentialreference [2]
integration/elytron/

[1] One subclass of this is not related to elytron but should be moved to core too. I haven't looked closely but it uses vault, which may be why it is in full. But we can use vault in the core testsuite now.

[2] Currently using Arquillian.