[#371] Add ConfigurationBuilder for flexible config management

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[Copilot]

Pull Request Overview

This PR introduces a ConfigurationBuilder for flexible configuration management, replacing the previous singleton-based configuration approach with a more modular and testable design.

• Implements ConfigBuilder class to replace imperative configuration initialization
• Updates HTTP status code error handling to support dynamic configuration changes
• Refactors test files to use destructured imports and improve test reliability

Reviewed Changes

Copilot reviewed 11 out of 15 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
lib/config.js	Major refactoring to add ConfigBuilder class and replace singleton pattern
lib/context/trace/span-recorder.js	Updates to use new HTTP status code error handling
lib/instrumentation/http/http-status-code-errors-builder.js	Adds singleton pattern for HTTP status code error management
index.js	Updates to use ConfigBuilder instead of direct getConfig
test/config.test.js	Updates to use destructured imports and adds tests for HTTP status code error handling
test/support/agent-singleton-mock.js	Updates imports to include clear function
test/client/grpc-fixture.js	Updates to use new configuration structure
test/client/grpc-unary-rpc.test.js	Updates to use destructured imports
test/agent/env-config.test.js	Updates to use destructured imports
test/instrumentation/module/undici.test.js	Makes test assertions more dynamic for remote address
test/instrumentation/module/http.test.js	Makes test assertions more dynamic for remote address

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