Symfony version(s) affected: 5.2 (also 5.1)

Description
When running multiple functional tests that request pages that include forms using an EntityType, there is a memory leak. Does not occur with symfony/doctrine-bridge 5.0.x.

How to reproduce
Reproducer (readme has instructions).

Possible Solution
I'm looking for help tracking down the problem. I think it's caused by #34550 and/or #30994 but I'm not positive.

I think, in your tests, when browsing multiple pages, one or more of which has a form that includes an EntityType, it is not cleaned up/reset between requests.

Additional context

• Blackfire comparison of the reproducer between symfony/doctrine-bridge 5.0 and 5.2. Nothing jumped out at me but I don't have any experience with blackfire.
• [DoctrineBridge] Massive memory usage increase in 5.1 #38890 seems very related.