Increase CI timeout for Core, Identity, and Serialization

[alzimmermsft]

Description

Increases the pipeline timeout for the Core, Identity, and Serialization pipelines as they effectively run the entire repo and with the recent introduction of new injected steps by 1ES they are frequently timing out. The timeout changed from 60 minutes to 90 minutes.

Additionally deletes the live test CI job as this in incorporated into every client-based pipeline and is no longer needed.

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.