Registry tool: upload discovery results in quota exhaustion when run against hosted registry

[hansatgoogle]

When running registry upload discovery against a hosted version of registry, after a number of successful uploads, the tool starts to be rate limited and encounters errors for RATE_LIMIT_EXCEEDED. The default limit appears to be 1200 requests per minute: quota_limit:RequestsPerProjectPerUserPerMinute quota_limit_value:1200. I was rate limited after uploading 52 specs.

A couple options I see to make the experience smoother:

• Add a max flag to upload discovery for the max number of APIs to upload and default to something relatively small like 25.
• Reduce the default number of jobs in the command. This would require some testing to see if reducing is actually slow enough to prevent rate limiting. Obviously this would depend a bit on the environment.
• Don't make a change to the registry tool and instead increase the default RequestsPerProjectPerUserPerMinute quota limit.

[theganyo]

Since the quota is set per instance and not per client, raising the limit might be a good idea.

That said, we still should handle things better on the client side... It seems like we don't have any fallback in place on the client when we're rate limited. I wonder if we should do that instead of simply failing?