Remove Spring Milestone repository

[rujche]

Description

• Remove Spring Milestone repository
• This repository won't be used anymore, and Azure DevOps pipeline will not enable network access.
• Related PR: Segregate Docker-dependent tests to GitHub Actions workflow #49481

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.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[Copilot]

Pull request overview

Removes the Maven profile that adds the Spring Milestone repository from the azure-client-sdk-parent parent POM, aligning the build with the intent to stop using that external repository as pipelines move toward restricted network access.

Changes:

• Deleted the external-dependency-version-overrides Maven profile that configured https://repo.spring.io/milestone for version override test runs.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.