👷 ci(workflow): Update workflow triggers and remove failed workflow

[h7ml]

Fixes

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PR Checklist

Please convert it to a draft if any of the following conditions are not met. Reviewers may skip over until all the items are checked:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• In case of non-backward compatible changes, reviewer should check this item as a write-off, and add details in Backward Compatibility section

Backward Compatibility

More information

• Changed the workflow at https://github.com/dgiot/dgiot/blob/master/.github/workflows/gitee-repos-mirror.yml to be manually triggered, as the owner @h7ml of the dst_key and dst_token has left the organization and repository, resulting in a lack of permissions for these keys.
• Left the organization, and receiving failure emails from the workflow daily, causing unwanted spam emails.
• Suggested changing the values of the private key and token fields to be managed by the repository and organization admins.

Details can be found in the documentation at https://github.com/Yikun/hub-mirror-action.

Mainly for workflow organization:

• Adjusted trigger mode to manual for .github/workflows/gitee-repos-mirror.yml and .github/workflows/label.yml.
• Removed .github/workflows/build_slim_packages.yaml due to continuous failures in build_slim_packages.