Sheets Connector TypeError: doc.useServiceAccountAuth is not a function

My last measurement using the sheets connector was on 2024-04-01

```
TypeError: doc.useServiceAccountAuth is not a function
at SheetsConnector.getSheet (AutoWebPerf/src/connectors/sheets-connector.js:47:15)
at SheetsConnector.getTestsSheet (AutoWebPerf/src/connectors/sheets-connector.js:56:32)
at SheetsConnector.getTestList (AutoWebPerf/src/connectors/sheets-connector.js:236:53)
at AutoWebPerf.run (AutoWebPerf/src/awp-core.js:315:38)
at Object.begin (AutoWebPerf/src/cli.js:193:17)
at Object. (AutoWebPerf/awp:8:7)
at Module._compile (node:internal/modules/cjs/loader:1376:14)
at Module._extensions..js (node:internal/modules/cjs/loader:1435:10)
at Module.load (node:internal/modules/cjs/loader:1207:32)
at Module._load (node:internal/modules/cjs/loader:1023:12)
```

Apparently, it's now required to instantiate the auth separately.
https://stackoverflow.com/a/76981493