Replace local context.Background() calls with global context in notebook controller tests

[coderabbitai]

Problem

The notebook controller tests in components/odh-notebook-controller/controllers/notebook_controller_test.go contain 15 instances of local context.Background() calls that should be replaced with the global context defined in suite_test.go.

Current State

• Tests create individual contexts with ctx := context.Background() in each It block
• Global context is properly set up in suite_test.go with ctx, cancel = context.WithCancel(context.Background()) in BeforeSuite
• This creates architectural inconsistency and bypasses proper cancellation capabilities

Benefits of Using Global Context

1. Proper cancellation support - Global context has context.WithCancel() for cleanup when tests are interrupted
2. Consistency - All tests use the same context management approach
3. Resource management - Global context is properly managed in test lifecycle
4. Performance - Eliminates unnecessary context creation overhead

Scope

Replace all 15 instances of:

It("Should do something", func() {
    ctx := context.Background()
    // test code...
})

With:

It("Should do something", func() {
    // Use global ctx directly
    Expect(cli.Create(ctx, resource)).Should(Succeed())
    // test code...
})

References

• Original discussion: RHOAIENG-23751: Add finalizer to clean up OAuthClients on notebook deletion #605 (comment)
• Related PR: RHOAIENG-23751: Add finalizer to clean up OAuthClients on notebook deletion #605

Acceptance Criteria

• Remove all 15 instances of local context.Background() creation
• Verify all tests use the global ctx variable consistently
• Ensure test functionality remains unchanged
• Update any similar patterns in other test files if found