Backport rpc errors

[agkogkakis]

These rpc errors are used by Vitess14 and are missing from our fork.
The end result is that some errors returned from the vtgate are interpreted as Unrecognized errors and not as CLUSTER_EVENT, READ_ONLY errors by the java client

Error prior to back port

	at io.vitess.jdbc.VitessConnection$1.run(VitessConnection.java:537)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.sql.SQLNonTransientException: Vitess vtgate error: message: "vttablet: rpc error: code = Code(17) desc = operation not allowed in state NOT_SERVING"
code: UNKNOWN_ENUM_VALUE_Code_17

Error with back port

	... 3 common frames omitted
Caused by: java.util.concurrent.ExecutionException: java.sql.SQLNonTransientException: Vitess vtgate error: message: "vttablet: rpc error: code = Code(17) desc = operation not allowed in state NOT_SERVING"
code: CLUSTER_EVENT

[makmanalp]

🚢