Feature/aci test refactor

[mmckechney]

This pull request refactors and extends the external integration test automation for SQL Server and PostgreSQL, improves test script reliability, and updates documentation and helper scripts to match the new structure. The main improvements are the separation of SQL Server and PostgreSQL external test runners, enhanced dynamic firewall handling, and corresponding updates to helper scripts and documentation.

Test runner separation and enhancements:

• Split the previous combined test runner run_all_external_tests_in_aci.ps1 into two scripts: run_all_sqlserver_external_tests_in_aci.ps1 (for SQL Server) and the new run_all_postgres_external_tests_in_aci.ps1 (for PostgreSQL), each dynamically filtering tests based on deployed platforms. The SQL Server script was renamed and PostgreSQL logic was moved to its own script. [1] [2]
• Updated the SQL Server test runner to focus only on SQL Server tests, removing all PostgreSQL logic and related platform checks. [1] [2]
• The new PostgreSQL test runner script dynamically determines which compute platforms are available and only runs the relevant PostgreSQL tests, skipping unavailable combinations with clear messaging.

Firewall and reliability improvements:

• Improved grant_identity_permissions.ps1 to automatically detect and add blocked client IP addresses to the firewall, retry permission grants up to three times, and clean up any dynamically-created firewall rules after execution.

Helper script and documentation updates:

• Updated Build_Images.bat and container_prompts.bat to point to the new, separate SQL Server and PostgreSQL test runner scripts, and adjusted working directory paths to a new location. [1] [2] [3] [4]
• Updated .github/copilot-instructions.md to document the new test runner scripts and clarify how external tests are executed.

These changes make the test automation more modular, robust, and easier to maintain.
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