Ensure okhttp sender dispatchers are bound and handle RejectedExecutionException

[jack-berg]

#8276 but for okhttp dispatchers, which are default to an unbounded thread pool:

opentelemetry-java/exporters/sender/okhttp/src/main/java/io/opentelemetry/exporter/sender/okhttp/internal/OkHttpUtil.java

Lines 32 to 41 in 420f052

	public static Dispatcher newDispatcher() {
	return new Dispatcher(
	new ThreadPoolExecutor(
	0,
	Integer.MAX_VALUE,
	60,
	TimeUnit.SECONDS,
	new SynchronousQueue<>(),
	createThreadFactory("okhttp-dispatch")));
	}

[shema-boris]

Hi @jack-berg, I’d like to work on this issue. Would you assign it to me?