Integrate launchTestNode with current test suites

[arboleya]

The idea is to update tests to use an isolated node via launchTestNode.

Then, we can try running tests in parallel / concurrently again.

Past experiments have been successful in this regard.

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Must be done after:

• feat!: add launchTestNode utility #1356

And will probably fix:

• New flaky tests #1755

[arboleya]

@nedsalk It would be fantastic to have a draft PR for this, after:

• feat!: add launchTestNode utility #1356

Like a small POC proving the workings of the former and demoing it in the real world.

cc @danielbate

[danielbate]

As part of this and with the merging of #2378, can we add the @group browser tag to tests also? The imports will need to be using the typegen paths.