#1858 add ThreadPoolHierarchicalTestExecutorService as optional alternative to ForkJoinPoolHierarchicalTestExecutorService (resolve JUnit 5 + Selenium 4 + Parallelism-issues)

[christophs78]

Overview

This draft-PR ist kind of a POC how we may able to solve #1858 and SeleniumHQ/selenium#9359.
I´d like to collect your feedback before investing more time into this PR.

IMO ForkJoinPoolHierarchicalTestExecutorService still should be default for parallel execution. ThreadPoolHierarchicalTestExecutorService may become kind of an configureable alternative for special usecases.

(Some more details regarding the root cause for this issue see #1858 (comment))

CC @titusfortner

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Definition of Done

• There are no TODOs left in the code
• Method preconditions are checked and documented in the method's Javadoc
• Coding conventions (e.g. for logging) have been followed
• Change is covered by automated tests including corner cases, errors, and exception handling
• Public API has Javadoc and @API annotations
• Change is documented in the User Guide and Release Notes
• All continuous integration builds pass

[christophs78]

superseded by #2806