Feature: Support unlimited sleep duration in SLEEP function

[wubx]

Summary
The current SLEEP() function in Databend has a hard limit of 3 seconds, which is insufficient for certain testing and development scenarios. This proposal suggests making the
sleep duration configurable or supporting larger values, including potentially infinite duration (+inf).

Current Behavior

SELECT SLEEP(5);

Error:
APIError: QueryFailed: [1006]The maximum sleep time is 3 seconds. Requested: 5s

Expected Behavior

The SLEEP() function should support:
1. Longer sleep durations (e.g., minutes or hours) for testing scenarios
2. Optionally support +inf for infinite sleep (similar to Snowflake's SYSTEM$WAIT)

Use Cases

1. Integration Testing: Simulating long-running queries or processes
2. Connection Testing: Testing timeout behaviors and connection pooling
3. Rate Limiting: Implementing delays in ETL pipelines
4. Development/Debugging: Pausing execution for manual inspection

Proposed Solutions

Option 1: Increase or Remove Hard Limit

- Remove the 3-second hard limit entirely

Option 2: Make it Configurable

Add a configuration parameter:
[query]
max_sleep_seconds = 3600  # Default: 3600 (1 hour), 0 for unlimited


Reference

Snowflake's SYSTEM$WAIT function supports similar functionality:
- https://docs.snowflake.com/en/sql-reference/functions/system_wait