- some tests are notoriously flaky
- increase resource limits for the testsuite to allow stronger stress tests
- provide a "quick" variant of BufferProviderLoad_test with lowered requirements
Furthermore, investigate test scaffolding in `DummyBuilderContext`,
which was broken due to the clean-up in `DiagnosticOutputSlot`.
It seems that only some placeholder instances are required here,
so that we might be successful with just instantiating the `UnimplementedConnection`
__TODO__: need to supply slightly more implementation into the latter,
so that we're able at least to ''create'' such a connection stub.