Should scrapy.utils.python.WeakKeyCache be deprecated?

[noviluni]

Summary

I can't find any reference to scrapy.utils.python.WeakKeyCache (except in tests) and I think that it should be deprecated.

Motivation

Keeping non-used and non-documented code makes the codebase harder to maintain.

Describe alternatives you've considered

As it's tested we could keep it, but I don't think it's a good idea.

[wRAR]

Looks like its (last) usage was removed in 332bf3b

[kshitijcode]

I can clean this up. Is it up for grabs? Can someone assign this to me, please?
@Gallaecio @wRAR

This would be my first open-source contribution :)

[Gallaecio]

@kshitijcode No need to ask first, feel free to go ahead! 🙂

[kshitijcode]

@Gallaecio @wRAR
I have raised the PR with the necessary changes: #4701
But I am not sure what is failing the tests.

Tests pass successfully locally after adding -W ignore::pytest.PytestDeprecationWarning. to tox.ini
I am not really sure whats breaking in Azure Pipelines.

[wRAR]

@kshitijcode the test failure is unrelated to your changes, I've created #4702 to track it