test(ffe): enable .NET EVP flagevaluation egress

[leoromanovsky]

Motivation

.NET needs route-level system-test coverage for flag-evaluation EVP delivery through the Datadog Agent, direct intake, and the serverless sidecar.

Linear: FFL-1492

Changes

• Enable the three .NET flag-evaluation egress cases at v3.53.0:
  • Datadog Agent
  • agentless direct intake
  • agentless serverless sidecar
• Assert /api/v2/flagevaluation payload aggregation, selected route, direct intake host and status, direct DD-API-KEY authentication, and zero events on unused routes.
• Keep the remaining .NET flag-evaluation behavior cases marked missing_feature (FFLSDK-28).

Decisions

• Activate only the three egress cases validated against the branch-built tracer.
• Use the same evaluation fixture and expected count in every topology.
• Require direct-intake route isolation and raw DD-API-KEY authentication.

Validation

• ./format.sh -- passed.
• Focused TEST_THE_TEST manifest validation -- 32 passed.
• Manifest parsing confirmed that only the Agent, direct, and sidecar egress cases are enabled; the basic flag-evaluation contract remains disabled.
• ./build.sh dotnet -w poc -- passed against the branch-built tracer package.
• Datadog Agent flag-evaluation egress -- 1 passed in 66.11s.
• Agentless direct flag-evaluation egress -- 1 passed in 14.59s.
• Agentless serverless-sidecar flag-evaluation egress -- 1 passed in 14.79s.

Workflow

1. ⚠️ Create your PR as draft ⚠️
2. Work on your PR until CI passes.
3. Keep test-logic review with the RFC owner; ask the R&P team in #apm-shared-testing for framework or non-obvious harness changes.

Note

For system-test framework or scenario help, use #apm-shared-testing.

Reviewer checklist

• Test logic has RFC-owner review.
• Any framework or scenario change has R&P review in #apm-shared-testing.

[github-actions]

CODEOWNERS have been resolved as:

tests/ffe/test_exposure_egress.py                                       @DataDog/feature-flagging-and-experimentation-sdk @DataDog/system-tests-core
tests/ffe/utils/exposures.py                                            @DataDog/feature-flagging-and-experimentation-sdk @DataDog/system-tests-core
.github/workflows/run-end-to-end.yml                                    @DataDog/system-tests-core
manifests/cpp_httpd.yml                                                 @DataDog/dd-trace-cpp
manifests/cpp_nginx.yml                                                 @DataDog/dd-trace-cpp
manifests/dotnet.yml                                                    @DataDog/apm-dotnet @DataDog/asm-dotnet
manifests/golang.yml                                                    @DataDog/dd-trace-go-guild
manifests/java.yml                                                      @DataDog/asm-java @DataDog/apm-java
manifests/nodejs.yml                                                    @DataDog/dd-trace-js
manifests/php.yml                                                       @DataDog/apm-php @DataDog/asm-php
manifests/python.yml                                                    @DataDog/apm-python @DataDog/asm-python
manifests/ruby.yml                                                      @DataDog/ruby-guild @DataDog/asm-ruby
manifests/rust.yml                                                      @DataDog/apm-rust
mirror_images.lock.yaml                                                 @DataDog/system-tests-core
mirror_images.yaml                                                      @DataDog/system-tests-core
tests/ffe/README.md                                                     @DataDog/feature-flagging-and-experimentation-sdk @DataDog/system-tests-core
tests/ffe/test_flag_eval_evp.py                                         @DataDog/feature-flagging-and-experimentation-sdk @DataDog/system-tests-core
tests/test_the_test/scenarios.json                                      @DataDog/system-tests-core
tests/test_the_test/test_compute_libraries_and_scenarios.py             @DataDog/system-tests-core
tests/test_the_test/test_group_rules.py                                 @DataDog/system-tests-core
tests/test_the_test/test_mock_ffe_agentless_backend.py                  @DataDog/feature-flagging-and-experimentation-sdk @DataDog/system-tests-core
utils/_context/_scenarios/__init__.py                                   @DataDog/system-tests-core
utils/_context/_scenarios/agentless_endtoend.py                         @DataDog/system-tests-core
utils/_context/containers.py                                            @DataDog/system-tests-core
utils/interfaces/__init__.py                                            @DataDog/system-tests-core
utils/proxy/core.py                                                     @DataDog/system-tests-core
utils/proxy/ports.py                                                    @DataDog/system-tests-core
utils/scripts/libraries_and_scenarios_rules.yml                         @DataDog/system-tests-core
tests/ffe/test_exposures_datadog_agent.py                               @DataDog/feature-flagging-and-experimentation-sdk @DataDog/system-tests-core

[datadog-official]

🎉 All green!

❄️ No new flaky tests detected

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[linear-code]

FFL-1492

[leoromanovsky]

Replaced by #7603.