Fix passing Sentry URL attribute
Fix passing Sentry URL attribute

Sentry's provider expects this value to be configured using the JSON
data payload and not from the attribute itself.

Signed-off-by: Leandro López (inkel) <b15bb9c509bcf4cfab9e5af881983cdb5d3cb233@grafana.com>

raintank/grafana-api-golang-client