feat: Recover pending tasks while pod restart. (#7073)
### What problem does this PR solve?
If you deploy Ragflow using Kubernetes, the hostname will change during
a rolling update. This causes the consumer name of the task executor to
change, making it impossible to schedule tasks that were previously in a
pending state.
To address this, I introduced a recovery task that scans these pending
messages and re-publishes them, allowing the tasks to continue being
processed.
### Type of change
- [ ] Bug Fix (non-breaking change which fixes an issue)
- [x] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):
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Co-authored-by: liuzhenghua-jk <liuzhenghua-jk@360shuke.com>