Remove dynamic schemas from Cube

What does this MR do and why?

Remove dynamic schemas from Cube

Dynamic schemas have potential issues, so removing the functionality

Related to https://gitlab.com/gitlab-org/gitlab/-/issues/494516+

Screenshots or screen recordings

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Before	After

How to set up and validate locally

1. Create a new funnel or update existing funnel by making an api call to /funnel-schemas endpoint in configurator

   POST http://{analytics-configurator-endpoint}/funnel-schemas
   Authorization: Basic [AUTH_USERNAME] [AUTH_PASSWORD]
   Content-Type: application/json
   
   {
     "project_ids": ["gitlab_project_20001"],
     "funnels": [
       {
         "name": "completed_purchase",
         "schema": "SELECT (SELECT max(derived_tstamp) FROM gitlab_project_20001.snowplow_events) as x, windowFunnel(3600)(toDateTime(derived_tstamp), page_urlpath = ''/page1.html'', page_urlpath = ''/page2.html'') as step FROM gitlab_project_20001.snowplow_events",
         "state": "created"
       }
     ]
   }

   OR

   Run GDK locally. Create a new funnel in any repository.

2. Visit an analytics dashboard, with the funnel added to it.

3. Confirm that the funnel no longer loads but the rest of the dashboard works as expected.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.