Restore Cloud Composer default connection

[lorenh]

In Cloud Composer 2 (Version: 2.9.3+composer), I started getting a warning in several of my tasks `WARNING - Connection schemes (type: google_cloud_platform) shall not contain '_' according to RFC3986.` I went into my Connections and set the bigquery_default connection type to Google Bigquery instead of Google Cloud, not realizing it was a default connection. Now I'm getting an error:  

google.api_core.exceptions.BadRequest: 400 GET  https://bigquery.googleapis.com/bigquery/v2/projects/[REDACTED]&prettyPrint=false:  Some rows belong to different partitions rather than destination partition

When i click the url, i get a page with this message:

{
  "error": {
    "code": 401,
    "message": "Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.",
    "errors": [
      {
        "message": "Login Required.",
        "domain": "global",
        "reason": "required",
        "location": "Authorization",
        "locationType": "header"
      }
    ],
    "status": "UNAUTHENTICATED",
    "details": [
      {
        "@type": "type.googleapis.com/google.rpc.ErrorInfo",
        "reason": "CREDENTIALS_MISSING",
        "domain": "googleapis.com",
        "metadata": {
          "method": "google.cloud.bigquery.v2.JobService.GetQueryResults",
          "service": "bigquery.googleapis.com"
        }
      }
    ]
  }
}

 How do I restore the default credentialed connection for Cloud Composer?