BigQuery source connector is failing with "Not found: Dataset" error, but the error references a completely incorrect dataset identifier that doesn't exist.

### Connector Name

source-bigquery

### Connector Version

BigQuery v0.4.5

### What step the error happened?

None

### Relevant information

**Problem**: The connection was working previously but is now consistently failing. The BigQuery source connector is correctly querying the right dataset, but BigQuery returns an error stating it cannot find dataset with a different name - a completely different and non-existent dataset identifier. The user has never queried or configured this malformed dataset name.

**Root Cause:** This appears to be a bug in the BigQuery source connector related to how it handles billing export table names. The connector is somehow corrupting the dataset identifier, extracting parts of the table name, adding a location suffix (`_us`), and combining it with what appears to be a template/sample project name (`tenant-project-billing-sample`). This matches a previously reported GitHub issue [#59675](https://support.airbyte.com/hc/requests/59675) with similar dataset name corruption.

**Verified Data:**
- Table type: BASE TABLE (not a view)
- Table exists and is queryable: 59,380,037 rows, ~50GB
- Metadata query confirms table is valid and accessible
- Source connection test passes successfully
- Connector is making correct API request: `GET .../projects/.../datasets/billing_export_sample/tables`

**Impact**: Critical - the connection has been failing for multiple days (since at least May 16, 2026). This is blocking billing data sync from BigQuery to Snowflake. The user cannot work around this issue without a connector fix.

I add 2 log files: 1 that was successful, 1 that failed.

[successful call.txt](https://github.com/user-attachments/files/28139108/successful.call.txt)
[failed call.txt](https://github.com/user-attachments/files/28139109/failed.call.txt)

** Investigation into why the BigQuery source connector is corrupting the dataset identifier for billing export tables, and either a patch/workaround or connector version update to resolve the issue.

### Relevant log output

```shell

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### Contribute

- [ ] Yes, I want to contribute

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**Internal Tracking:** https://github.com/airbytehq/oncall/issues/12686