Removing flaky tests which are not compatible configurations and not required henceforth

[Kaniska (Kaniska244)]

Description

This PR removes flaky and incompatible test configurations from the test-all.yaml workflow that are no longer required. These combinations were producing unreliable results or testing configurations that are not supported, adding noise to CI without providing meaningful coverage.

Changes

Excluded incompatible feature / base image combinations in the test matrix:

• oryx on ubuntu:jammy
• oryx on mcr.microsoft.com/devcontainers/base:ubuntu
• docker-in-docker on mcr.microsoft.com/devcontainers/base:debian
• docker-outside-of-docker on mcr.microsoft.com/devcontainers/base:debian
• docker-in-docker on mcr.microsoft.com/devcontainers/base:ubuntu
• docker-outside-of-docker on mcr.microsoft.com/devcontainers/base:ubuntu

Separated iptables-isolation scenarios out of the docker-in-docker job:

• Added a step that strips the docker_with_default_iptables and docker_with_default_iptables_ubuntu scenarios from test/docker-in-docker/scenarios.json before running, so they run in a dedicated iptables-isolation job instead of the general scenario run.

Motivation

• Eliminates flaky test failures caused by unsupported/incompatible configurations.
• Reduces CI noise and speeds up test runs by not exercising combinations that are not required going forward.
• Keeps iptables-isolation coverage intact by moving it to a separate, isolated job.

Testing

• CI (test-all workflow) exercises the updated matrix and confirms the excluded combinations are no longer run while remaining scenarios continue to pass.