(7.4.z) Update testsuite/integration/multinode tests to run on SE 17

Adapt the WFLY-15001 and WFLY-15199 changes in testsuite/integration/multinode to the EAP 7.4.x branch to allow the tests to run in an SE 17 environment where legacy security doesn't exist.

AFAICT the gist of the upstream change was to convert the authentication of internode calls from the use of a legacy security realm to using local auth. That was done upstream by changing the xsl transformation applied to the config. I could do the same (which would then apply to non-elytron/non-SE17 testing) or I could adjust the CLI script that adapts the config to SE 17 to also update these specific-to-this-testsuite resources. I think I'll start with the latter approach.