Migrate App Proxy Coordinator lock infrastructure to valkey-glide

## Objective

Migrate App Proxy Coordinator's lock infrastructure from redis-py to valkey-glide.

## Files to modify

- `src/ai/backend/appproxy/coordinator/dependencies/infrastructure/redis.py`
- Lines 66-70: redis_lock client creation
- Line 7: Import statements
- **Note on line 65:** "Keep redis_lock for distributed locking (not yet migrated)" - this will be resolved
- `src/ai/backend/appproxy/coordinator/server.py` (lines 916-926)
- `init_lock_factory()` function

## Tasks

- [ ] Replace redis-py client with valkey-glide in redis.py
- [ ] Update RedisLock initialization in server.py
- [ ] Update import statements
- [ ] Remove "not yet migrated" comment
- [ ] Test coordinator locking functionality

## Dependencies

Depends on: Migrate RedisLock implementation

## Related

Part of BA-2585 - Retire redis-py entirely

JIRA Issue: BA-3270