SRVOCF-846: Migrate remaining unit tests to MSW

[Cragsmann]

Summary

• Migrate 4 test files from vi.mock service-level mocking to MSW (Mock Service Worker) network-level mocking
• Real service code now runs in tests, with MSW intercepting HTTP calls at the network layer
• useClusterService.test.tsx kept as-is since useK8sWatchResource is an SDK hook, not HTTP

Migrated files

File	Tests	Key changes
OcpClusterService.test.ts	4	Replaced mockGet/mockPost with consoleFetchJSON bridge + MSW handlers for K8s API
UserAvatar.test.tsx	14	Removed mockFetchUserInfo, real GithubService runs with MSW intercepting GitHub API
FunctionsListPage.test.tsx	19	Removed mockUseSourceControl, MSW handles /user and /search/repositories
FunctionCreatePage.test.tsx	5	Removed 3 service mocks, MSW handles full create flow (backend API + GitHub API + K8s API)

Pattern

The consoleFetchJSON bridge in the SDK mock converts the OpenShift SDK's consoleFetchJSON into real fetch calls so MSW can intercept them. useK8sWatchResource stays as vi.mock since it's an SDK React hook, not HTTP.

Test plan

• All 125 tests pass (yarn test)
• No regressions in existing test files