Default time column selectors do not work with BasicAuth

[oplehto]

With BasicAuth enabled the lookup of valid time column values fails:

Code: 516. DB::Exception: Invalid authentication: 'true' HTTP Authorization scheme is not supported. (AUTHENTICATION_FAILED) (version 23.8.6.16 (official build))

The culprit seems to be this bit:

clickhouse-grafana/src/datasource/datasource.ts

Lines 100 to 102 in a521a07

	if (options.basicAuth) {
	requestOptions.headers.Authorization = options.basicAuth;
	}

Which sets the auth header:

x-ds-authorization: true

At least with Server mode it works just by removing that part of code. Not sure if that's a working solution for proxy mode though..