Confirm model response from vertex-gecko

Prior to this MR the response from vertex-gecko was being ran through a markdown extraction function as a previous attempt to ensure a model response. In doing that, the model response was returning blank values as responses from vertex_gecko are not markdown responses, rather they are JSON responses. This is because vertex-gecko is a generative code thing different than what vertex_bison returns a markdown code block. This MR captures that JSON response successfully and should allow for model responses from vertex_gecko.

This MR also removes sentry.

cc @jayswain @srayner