Suppress internal sdkstats HTTP pipeline logs from appearing in user's traces

[rads-1996]

Description

Fixes - #45910

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

[Copilot]

Pull request overview

This PR addresses noisy INFO-level HTTP pipeline logs emitted by the internal sdkstats/statsbeat exporter, preventing those internal requests from showing up in user console output (per issue #45910).

Changes:

• Conditionally omits HttpLoggingPolicy when initializing the sdkstats/statsbeat exporter pipeline.
• Adds a corresponding entry to the package changelog.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
sdk/monitor/azure-monitor-opentelemetry-exporter/azure/monitor/opentelemetry/exporter/export/_base.py	Skips adding HttpLoggingPolicy for sdkstats exporters to suppress internal HTTP request/response logs.
sdk/monitor/azure-monitor-opentelemetry-exporter/CHANGELOG.md	Documents the bug fix in the unreleased section.

[rads-1996]

Before Change -

After Change -