Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.36.1 to 1.44.0.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](https://github.com/grpc/grpc-go/compare/v1.36.1...v1.44.0)
Also update akamai-purger integration test to avoid experimental API.
The `conn.GetState()` API is marked experimental and may change behavior
at any time. It appears to have changed between v1.36.1 and v1.44.0,
and so the akamai-purger integration tests which rely on it break.
Rather than writing our own loop which polls `conn.GetState()`, just
use the stable `WaitForReady(true)` connection option, and apply it to
all connections by setting it as a default option in the dial options.
2ec03b377b