[backport] gateway2/delegation: enable inherited policy overrides (#10470)

[shashankram]

Description

Backports 1bed380 from main

Adds the ability to override inherited policy fields when explicitly permitted by a parent route using the annotation delegation.gateway.solo.io/enable-policy-overrides. It supports a wildcard value "*" or a comma separated list of field names such as "faults,timeouts,retries,headermanipulation".

Functionally, a child RouteOption may only override the RouteOptions derived from its parent if the above annotation exists on the parent route. This is required to make the override behavior safe to use.

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Testing done:

• Translator tests for the new scenarios.
• Repro script provided by Arka

Testing steps

Use the examples added in the translator tests to verify the override behavior of inherited policies with delegation.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation TODO
• I have added tests that prove my fix is effective or that my feature works

[solo-changelog-bot]

Issues linked to changelog:
https://github.com/solo-io/solo-projects/issues/7315