Refactor some loops code and hook tests

[carmocca]

What does this PR do?

Assortment of minor changes

• Joined hook order tests
• Added hook order test for fit when no validation is run
• Tiny bit of typing
• Simplified the "should run validation" logic
• Simplified the update lr logic
• A test refactor

Reducing the diff for #7357

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[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@fe1c4ca). Click here to learn what that means.
The diff coverage is 100%.

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[tchaton]

LGTM !

[Borda]

wahy not use Mock? @awaelchli

[carmocca]

It's hard to use as there are several checks throughout our codebase for isinstance(LightningModule)

I've tried it in the past without success. You can give it a try if you feel confident :D

[Borda]

ok, so lest check if we have a ticket for mocking this kind of tests and if note create one...

[carmocca]

I don't think it's possible, maybe if we could mock the inherited classes defining all these hooks...

No explicit issue for it. Has been brought up a few times across PRs though