Simplify controller and add E2E tests for status reporting

[yrobla]

Remove duplicate backend discovery from VirtualMCPServer controller, delegating all backend discovery and health monitoring to the vMCP runtime via StatusReporter.

Controller simplification:

• Remove discoverBackends() method (~130 lines) from controller
• Backend discovery now handled by vMCP runtime with K8sReporter
• Controller focuses on infrastructure: RBAC, Deployment, Service, ConfigMap
• vMCP runtime handles: backend discovery, health monitoring, status updates

Test cleanup:

• Remove virtualmcpserver_discover_backends_test.go (controller-side tests)
• Remove TestDiscoverBackendsWithExternalAuthConfigIntegration from virtualmcpserver_externalauth_test.go
• Keep relevant auth conversion tests

E2E test additions:

• Add virtualmcp_status_reporting_test.go with comprehensive tests

Related-to: #3149

Large PR Justification

This is a cleanup pr, that removes substantial lines of code to replace with newer ones. It also includes tests to validate the new behaviour.

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[Copilot]

Pull request overview

This pull request simplifies the VirtualMCPServer controller by removing duplicate backend discovery logic (~130 lines) and delegating all backend discovery and health monitoring to the vMCP runtime via its StatusReporter mechanism. The change aligns with the architectural principle of separation of concerns: the controller manages infrastructure (RBAC, Deployment, Service, ConfigMap), while the vMCP runtime handles backend discovery, health monitoring, and status updates.

Changes:

• Removed discoverBackends() method from controller (delegated to vMCP runtime with K8sReporter)
• Removed controller-side backend discovery tests (virtualmcpserver_discover_backends_test.go)
• Removed integration test TestDiscoverBackendsWithExternalAuthConfigIntegration from virtualmcpserver_externalauth_test.go
• Added comprehensive E2E tests for status reporting (virtualmcp_status_reporting_test.go) with 2 test cases covering backend discovery, health monitoring, and failure recovery
• Added GetMCPServerDeployment helper function for E2E tests

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/e2e/thv-operator/virtualmcp/virtualmcp_status_reporting_test.go	New E2E test suite validating vMCP runtime status reporting for backend discovery and health monitoring
test/e2e/thv-operator/virtualmcp/helpers.go	Added GetMCPServerDeployment helper function to retrieve MCPServer deployments by name
cmd/thv-operator/controllers/virtualmcpserver_externalauth_test.go	Removed TestDiscoverBackendsWithExternalAuthConfigIntegration (170 lines) as backend discovery moved to runtime
cmd/thv-operator/controllers/virtualmcpserver_discover_backends_test.go	Deleted entire file (643 lines of controller-side backend discovery tests)
cmd/thv-operator/controllers/virtualmcpserver_controller.go	Removed discoverBackends method and unused imports (groups, aggregator); added comprehensive documentation explaining responsibility split

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[github-actions]

✅ Large PR justification has been provided. The size review has been dismissed and this PR can now proceed with normal review.

Large PR justification has been provided. Thank you!

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.91%. Comparing base (7da281b) to head (ca67a0c).

Additional details and impacted files

@@                Coverage Diff                @@
##           issue-3149-v2    #3468      +/-   ##
=================================================
- Coverage          64.95%   64.91%   -0.05%     
=================================================
  Files                396      395       -1     
  Lines              38577    38481      -96     
=================================================
- Hits               25057    24979      -78     
+ Misses             11575    11559      -16     
+ Partials            1945     1943       -2     

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