Improve error message thrown by AbstractResultSet$GrpcStreamIterator.computeNext()

**Is your feature request related to a problem? Please describe.**
While debugging a customer issue, we realized that in [some cases](https://.com/googleapis/java-spanner/blob/d617fb61eb0bba970c7cf4f43a4d50b54eb0f521/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/AbstractBaseUnitOfWork.java#L133), we have descriptive error messages that show which query triggered a DEADLINE_EXCEEDED error.

The specific error thrown in the case that was being debugged was from [here](https://.com/googleapis/java-spanner/blob/3f32f51d70ceacbea02439c0f48ad057b10fb570/google-cloud-spanner/src/main/java/com/google/cloud/spanner/AbstractResultSet.java#L785).

**Describe the solution you'd like**
It would be ideal if this branch could also throw an error that contains the query that was being executed.

**Describe alternatives you've considered**
N/A

**Additional context**
N/A

Description