Selecting too much data that overflows the gRPC packet limit still reports ERTooManyUserConnections

[aquarapid]

#6630 was supposed to address this, but the regex used to match and map the gRPC error message seems to have only handled the case where too much data was being inserted, not selected.

As a result, on current main, if you have a table with wide columns, I see:

mysql> select * from t1 limit 900;      
ERROR 1203 (42000): target: keyspace1.0.primary: vttablet: rpc error: code = ResourceExhausted desc = grpc: trying to send message larger than max (18015277 vs. 16777216)
mysql> 

Error 1203 is ERTooManyUserConnections; we want Error 1153 (ERNetPacketTooLarge).