ebs br: fail delete cr operation if backup meta is missing

[BornChanger]

What problem does this PR solve?

Closes #5196
Closes #5159

What is changed and how does it work?

If backup meta file doesn't exist during backup cr deletion, we should fail the backup cr deletion and remind users to do manual snapshots deletion.

Code changes

• Has Go code change
• Has CI related scripts change

Tests

• Unit test
• E2E test
• Manual test
• No code

Side effects

• Breaking backward compatibility
• Other side effects:

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release Notes

Please refer to Release Notes Language Style Guide before writing the release note.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[codecov-commenter]

Codecov Report

Merging #5199 (bfdbe6b) into master (34c19d4) will increase coverage by 1.90%.
The diff coverage is 0.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5199      +/-   ##
==========================================
+ Coverage   57.97%   59.87%   +1.90%     
==========================================
  Files         245      248       +3     
  Lines       29240    32534    +3294     
==========================================
+ Hits        16951    19480    +2529     
- Misses      10641    11302     +661     
- Partials     1648     1752     +104     

Flag	Coverage Δ
e2e	24.35% <ø> (?)
unittest	57.95% <0.00%> (-0.03%)	⬇️

[BornChanger]

/test pull-e2e-kind-br

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@BornChanger: The label(s) /pull-e2e-kind-br cannot be applied, because the repository doesn't have them.

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/test pull-e2e-kind-br

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@BornChanger: No presubmit jobs available for pingcap/tidb-operator@master

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/test pull-e2e-kind-br

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[BornChanger]

/retest

[BornChanger]

/cherry-pick release-1.5

[ti-chi-bot]

@BornChanger: The label(s) /release-1.5 cannot be applied, because the repository doesn't have them.

In response to this:

/cherry-pick release-1.5

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[ti-chi-bot]

@BornChanger: new pull request created to branch release-1.5: #5210.

In response to this:

/cherry-pick release-1.5

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