ci: fix flaky testcontainers tests

[ndr-brt]

What this PR changes/adds

Refactor EndToEnd tests to avoid flaky test executions when testcontainers is used.
Concepts:

• EmbeddedRuntime configurations are passed lazily through configurationProviders
• The configuration values in Participant subclasses are generated lazily (using the provided LazySupplier) during the EDC runtime startup so they will take into account eventual testcontainers ports used

Why it does that

avoid test flakyness by design

Further notes

• there still are two potential pityfalls in Participant: managementEndpoint and protocolEndpoint that are currently instantiated statically while they should follow the same pattern. It will be fixed in a subsequent PR to avoid clogging this one
• I will also provide some guidance in the documentation that will be useful also for downstream projects

Linked Issue(s)

Part of #4710

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[rafaelmag110]

Could we have the getFreePort lazily supplying ports instead? Does that make sense? Would that be simpler? I'm trying to get my head around this.