MOB-47082 metrics and concurrency

[ilonablazemeter]

Each PR must conform to Developer's Guide.

Quick checklist:

• Description of PR explains the context of change
• Unit tests cover the change, no broken tests
• No static analysis warnings (Codacy etc.)
• Documentation update ('available in the unstable snapshot' warning if necessary)
• Changes file inside site/dat/docs/changes directory, one-line note of change inside

[Copilot]

Pull request overview

Adds optional support for the new Happysocks ClickHouse-backed namespace, wiring it through the BlazeMeter reporter configuration and validating behavior via unit tests.

Changes:

• Introduce /v1/engine-ch namespace support via use_clickhouse in HappysocksClient / HappysocksEngineNamespace.
• Expose happysocks-use-clickhouse setting in the BlazeMeter reporter to toggle the ClickHouse namespace.
• Add/extend unit tests and update changelog/changes entry documenting the feature.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
bzt/utils.py	Adds ClickHouse namespace constant and propagates use_clickhouse to connect/emit namespaces.
bzt/modules/blazemeter/blazemeter_reporter.py	Reads happysocks-use-clickhouse and passes it to HappysocksClient.
tests/unit/test_bza.py	Adds coverage for ClickHouse namespace connect/emit and namespace selection behavior.
tests/unit/modules/test_blazeMeterUploader.py	Verifies reporter instantiates HappysocksClient with correct use_clickhouse argument.
bzt/modules/console.py	Updates urwid import paths (likely aligning with current urwid dependency layout).
site/dat/docs/changes/feat-support-for-clickhouse-happysocks-namespace.change	Adds the required one-line change note for the feature.
site/dat/docs/Changelog.md	Adds release notes for 1.16.50 describing the new namespace support and setting.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.86%. Comparing base (ea643e4) to head (9ecae4e).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1974      +/-   ##
==========================================
- Coverage   89.91%   89.86%   -0.04%     
==========================================
  Files          71       71              
  Lines       20182    20183       +1     
==========================================
- Hits        18145    18136       -9     
- Misses       2037     2047      +10     

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