refactor(jest): enable clearMocks

[JamieMagee]

Changes

• Sets clearMocks¹ in jest.config.ts (equivalent to calling jest.clearAllMocks² before each test)
• Removes any explicit calls to jest.clearAllMocks
• Fixes tests that were relying on faulty mock counts

This automatically clears mock calls, instances, contexts and results before every test. This makes it more difficult to write tests which rely on each other.

Context

#18768

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please tick one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

Footnotes

1. https://jestjs.io/docs/configuration#clearmocks-boolean ↩

2. https://jestjs.io/docs/jest-object#jestclearallmocks ↩

[renovate-release]

🎉 This PR is included in version 34.25.0 🎉

The release is available on:

• GitHub release
• 34.25.0

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