Bug fix to return authType as undefined if displayName is not set (#8731)

We noticed that if displayName is undefined this method would return the first auth type it found as getAuthTypeDisplayName() would return undefined.
If the displayName is undefined, we would not have a matchingTYpe and it should be undefined.

src/sql/workbench/services/connection/browser/connectionWidget.ts

@@ -915,6 +915,9 @@ export class ConnectionWidget extends lifecycle.Disposable {
 	}
 
 	private getMatchingAuthType(displayName: string): AuthenticationType {
+		if (!displayName) {
+			return undefined;
+		}
 		return find(ConnectionWidget._authTypes, authType => this.getAuthTypeDisplayName(authType) === displayName);
 	}