Update test infrastructure to use valkey-glide

## Objective

Migrate test utilities and test cases from redis-py to valkey-glide.

## Files to modify

- `tests/common/test_distributed.py`
- Line 16: Import statements
- Lines 35, 387: RedisLock usage
- Line 381: Redis client creation
- `tests/common/redis_helper/`
- `test_connect.py` (lines 8-12)
- `test_pipeline.py` (lines 7-9)
- `utils.py` (lines 17-20)
- `src/ai/backend/testutils/bootstrap.py` (line 18)
- Testcontainers usage

## Tasks

- [ ] Update test fixtures to use valkey-glide
- [ ] Replace Redis.from_url() with valkey-glide equivalent
- [ ] Update RedisLock test cases
- [ ] Verify testcontainers compatibility
- [ ] Run full test suite to ensure compatibility

## Related

Part of BA-2585 - Retire redis-py entirely

JIRA Issue: BA-3273