ATS11: Remove slow log feature

[bryancall]

Summary

Remove the built-in slow log feature from ATS. This functionality is better handled by log analysis tools and custom logging configurations rather than baked into the core.

Files to modify

The slow log touches the following areas:

Core

• src/proxy/http/HttpSM.cc - slow log logic in HTTP state machine
• src/proxy/http/HttpConfig.cc - slow log config handling
• include/proxy/http/HttpConfig.h - slow log config structs
• include/proxy/http/OverridableConfigDefs.h - overridable config entries

H2

• src/proxy/http2/Http2Stream.cc - H2 slow log integration
• src/proxy/http2/Http2CommonSession.cc - H2 session slow log
• src/proxy/http2/HTTP2.cc - H2 slow log config
• include/proxy/http2/HTTP2.h - H2 slow log declarations

Records / Config

• src/records/RecordsConfig.cc - slow log record definitions
• configs/records.yaml.default.in - default config values

Logging

• configs/logging.yaml.default - slow log format definition

Cripts

• include/cripts/Configs.hpp - cripts slow log bindings

Documentation

• doc/admin-guide/files/records.yaml.en.rst
• doc/developer-guide/api/functions/TSHttpOverridableConfig.en.rst
• doc/locale/ja/LC_MESSAGES/developer-guide/api/functions/TSHttpOverridableConfig.en.po

Tests

• tests/gold_tests/records/legacy_config/full_records.config