Restore all sinon stubs after each test

[acelaya]

Fixes #7033

Add a call to sinon.restore() in our tests bootstrap's beforeEach, so that all mocks are restored after each test.

This is necessary because sinon keeps track of all mocks created via sinon.stub(), and you need to either call restore() on the mock itself, or do it "globally" to ensure memory can be released.

If more than 10,000 stubs are created, then sinon prints a warning message.

Since having to remember to call restore() every time is error prone, this PR adds a global call that makes it unnecessary.

Before this PR, the tests output would include a line like this:

With these changese, that warning is no longer reported:

Considerations

This PR makes individual restore calls no longer needed, but I decided to not remove them here to reduce the noise.

[acelaya]

Since we are calling sinon.restore() after each test now, mocks need to be created before each test, not before all.

Also, the window.requestAnimationFrame.restore() call fails because this afterAll callback is invoked after the sinon.restore() call in the bootstrap's afterEach.

So I have moved the mock initialization to afterEach, and removed the restore call entirely, as it's no longer needed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.47%. Comparing base (b0fb2d6) to head (22f4ad1).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7338   +/-   ##
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  Coverage   99.47%   99.47%           
=======================================
  Files         271      271           
  Lines       10968    10968           
  Branches     2620     2620           
=======================================
  Hits        10910    10910           
  Misses         58       58           

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