test(aiohttp-server): make non-global tracer provider test deterministic

[DebadityaHait]

Description

Make test_non_global_tracer_provider deterministic by using the always-on sampler and a single request. The test now verifies that exactly one server span is exported through the supplied provider and checks its expected name, kind, method, status, and target.

This removes the statistical sampling bounds without weakening coverage of the non-global provider path.

Fixes #4811

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Focused test passed 10 consecutive runs
• aiohttp-server test suite: 34 passed
• Ruff and pre-commit checks
• aiohttp-server Pylint checks
• Pyright type checking

Does This PR Require a Core Repo Change?

• No.

Checklist

• Followed the style guidelines of this project
• Unit tests have been updated
• Changelog not required because this is a test-only change
• Documentation not required

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: DebadityaHait / name: debaditya (5759259)