stacks-node: choose how to handle sequential integration tests

[fdefelici]

Some integration tests cannot be run in parallel

Choose if we want to tag them (with a sequential tag) or using serial crate.

Here the trade-off:

• tagging them will allow to list/filter test based on sequential tag, but will need to explicitly configure them properly in nextest runner for sequential execution
• using serial crate, instead, we loose the filtering, but test serialization will happen automatically (no specific configuration to be done on the test runner)

NOTE: If we want to best from the two solution we could do both (tagging + serial) or to reduce the boilerplate we could improve pinny so that when "sequential" tag is used, automatically add "serial" crate attribute. (eventually this could be made configurable for generalization)

NOTE2: In case of new tag definition, remember to update the tag table in https://github.com/stacks-network/stacks-core/blob/master/CONTRIBUTING.md#testing (if not already present on "master" the table could be present on "develop" branch)