feat(query): Add external_block_rows metrics

[b41sh]

I hereby agree to the terms of the CLA available at: https://docs.databend.com/dev/policies/cla/

Summary

1. Add a new metrics external_block_rows to record the number of rows per block when calling the udf servers.
2. Fix the metrics external_request_duration and external_connect_duration to record data in milliseconds, and fix the metric data loss caused by the wrong record unit.
3. Create endpoints in the init_endpoints function.
4. Create semaphore in the init_semaphore function to make max threads permit in query level instead of transform level.

• fixes: #[Link the issue here]

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Explain why

Type of change

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe):

---

This change is 

[flaneur2020]

LGTM 👍

[github-actions]

Docker Image for PR

• tag: pr-17116-70916b0-1735189702

note: this image tag is only available for internal use,
please check the internal doc for more details.

[github-actions]

ClickBench Report

• hits: https://benchmark.databend.com/clickbench/pr/17116/12499576044/hits.html
• internal: https://benchmark.databend.com/clickbench/pr/17116/12499576044/internal.html
• load: https://benchmark.databend.com/clickbench/pr/17116/12499576044/load.html
• tpch: https://benchmark.databend.com/clickbench/pr/17116/12499576044/tpch.html

[sundy-li]

Perf test is to show performance with the latest release.

It is not related to this pr; it is also seen in the latest changes.