**Description**

This PR fixes a crash when handling `_InactiveRpcError` during retry
logic and ensures proper `timeout` propagation in
`RowIterator.to_dataframe`.

**Fixes**

**Retry Logic Crash**: Addressed an issue in
`google/cloud/bigquery/retry.py` where `_should_retry` would raise a
`TypeError` when inspecting unstructured `gRPC` errors (like
`_InactiveRpcError`). The fix adds robust error inspection to fallback
gracefully when `exc.errors` is not subscriptable.

**Timeout Propagation**: Added the missing `timeout` parameter to
`RowIterator.to_dataframe` in `google/cloud/bigquery/table.py`. This
ensures that the user-specified `timeout` is correctly passed down to
the underlying `to_arrow` call, preventing the client from hanging
indefinitely when the Storage API is unresponsive.

**Changes**

Modified `google/cloud/bigquery/retry.py`: Updated `_should_retry` to
handle `TypeError` and `KeyError` when accessing `exc.errors`.
Modified `google/cloud/bigquery/table.py`: Updated
`RowIterator.to_dataframe` signature and implementation to accept and
pass the `timeout` parameter.

The first half of this work was completed in PR #2354