Update to use `testing.T.Context`

In a lot of places in the tests we use the construct 

```go
ctx, cancel := context.WithCancel(context.Background())`
t.Cleanup(cancel)
```

This can be omitted in go1.25 and everywhere where a context is required `t.Context()` can be used.

/kind cleanup
/kind chore
/label "good first issue"