[TEST] split base settings in ClusterDiscoveryConfiguration between node and transport client

The default settings that are currently applied to the transport client are about discovery and gateway, modules that are not even loaded on the transport client. We can now remove the local gateway as it's not the default one anyway. Also, make sure that the discovery setting is only applied to the node, as it is not relevant for transport client.

Closes #8653
[TEST] Extend unicast ports generation to support more concurrent clusters

Make it possible to run multiple tests with unicast configuration, by assigning ports based on their test scope.
Every jvm still gets its own port range based on the jvm id, but we now make sure that the different jvms ranges never overlap. The global cluster gets a reserved port range, while SUITE and TEST scopes are treated equally, just assuming that they never run concurrently on the same jvm, thus ports can be safely reused.

Closes #8634
[TEST] make sure rest tests info is printed for any @Rest annotated test

We introduced the @Rest annotation a while ago for REST tests (see #7795), we have then to make sure that relevant info to reproduce failures gets printed out for any test that is marked with such annotation, not only for ElasticsearchRestTests

Closes #8680
[Docs] Fix missing comma in mapping
[TEST] remove duplicated tests.slow from randomized testing maven plugin conf