Suggestion(terminology): Error Mode - AIP-4221 #1676

In AIP-4221 Client-side retry, term error mode is used few times.

It's the only document that uses this term within AIP corpus.

This term could be replaced with something else due:

• mode is often assigned to object that perform actions, while paired with API reader might think API have an error mode
• it's very rare to see this term
• reader might think error mode is a concept and try to look it up

Possible Alternatives

• retryable errors
• errors with retryable status codes
• status codes that a client should retry