log_backup: store pending region info when giving up retry (#16624)

[ti-chi-bot]

This is an automated cherry-pick of #16624

What is changed and how it works?

Issue Number: Close #16469, Ref #16554

What's Changed:
This PR rearranged the lifetime of a observed region.
For now, we will try to keep it in subscription tracker from Start until End, even the start itself is failed.
So the RefreshObserver will be able to find and start its observe as expected.

This also added a test case for verifying #16554 has been fixed in master.

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Release note

Fixed a bug that may cause PiTR failed to observe the region.

[ti-chi-bot]

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[YuJuncen]

Close it for now... Maybe use #17067