fix(ado.net): translate SpannerException to SpannerDbException

[olavloite]

Translate SpannerException to SpannerDbException for the sync code paths in SpannerDataReader, to ensure consistency between the sync and async methods.

[gemini-code-assist]

Code Review

This pull request adds exception translation to the Read, CheckForRows, and NextResult methods in SpannerDataReader, and introduces a new unit test to verify exception handling during both synchronous and asynchronous reads. The reviewer feedback suggests replacing the lambda-based exception translation with direct try-catch blocks to avoid unnecessary delegate allocations on hot paths. Additionally, the reviewer recommends marking the new test with the [NonParallelizable] attribute because it modifies global environment variables and state, which could cause flakiness when tests are run in parallel.

[olavloite]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces exception translation in SpannerDataReader for the Read, CheckForRows, and NextResult methods to ensure SpannerException is properly mapped to SpannerDbException, and adds a corresponding unit test. The feedback suggests refactoring these newly added try-catch blocks by utilizing an existing SpannerDbException.TranslateException helper overload that accepts a lambda, which would make the code cleaner and more maintainable.