chore: support to delete failed backups when deleting cluster

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 50.00000% with 14 lines in your changes missing coverage. Please review.

Project coverage is 61.35%. Comparing base (0d4a0b5) to head (307c463). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
controllers/apps/transform_utils.go	43.75%	8 Missing and 1 partial :warning:
controllers/apps/transformer_cluster_deletion.go	44.44%	3 Missing and 2 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #8435 +/- ## ========================================== + Coverage 61.12% 61.35% +0.22% ========================================== Files 351 351 Lines 41743 41764 +21 ========================================== + Hits 25517 25623 +106 + Misses 13927 13828 -99 - Partials 2299 2313 +14 ``` | [Flag](https://app.codecov.io/gh/apecloud/kubeblocks/pull/8435/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apecloud) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/apecloud/kubeblocks/pull/8435/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apecloud) | `61.35% <50.00%> (+0.22%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apecloud#carryforward-flags-in-the-pull-request-comment) to find out more.

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