osd: fix removing key file timing (backport #13830)

[mergify]

The key file deletion process is in the shell script commonly used by all of encryption-open, encryption-open-metadata, and encryption-open-wal init containers. The key file is deleted at the encryption-open init container and encryption-open-metadata and encryption-open-wal init containers are failed to open the key file.

The key file is in the /etc/ceph folder. Unless that folder is shared, the key file anyway won't be available in the other init containers even if it is not deleted by these init containers. And it will naturally anyway be deleted after the init containers are completed. So The key file deletion process in shell scripts is unnecessary.

Fixes: #13737

Checklist:

• Commit Message Formatting: Commit titles and messages follow guidelines in the developer guide.
• Reviewed the developer guide on Submitting a Pull Request
• Pending release notes updated with breaking and/or notable changes for the next minor release.
• Documentation has been updated, if necessary.
• Unit tests have been added, if necessary.
• Integration tests have been added, if necessary.

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This is an automatic backport of pull request #13830 done by [Mergify](https://mergify.com).