text: Title: [BUG] DQ Anomaly Metrics should not be displayed when we do count aggregation on a categorical column
  Body: ## Describe the bug
  If we create a KPI with metric column type categorical and count as aggregation, DQ mean and Max graphs are displayed empty and DQ count graph is only displayed.
  
  ## Explain the environment
  - **Chaos Genius version**: v0.3.0
  
  ## Expected behavior
  DQ Graphs should not be displayed. We can't take mean/max for categorical values and DQ Count graph will be the same as the overall KPI graph.
  
  ## Screenshots
  ![Screenshot from 2022-01-05 17-01-18](https://user-images.githubusercontent.com/22439823/148242173-ef2e6296-cdb8-4b1c-8cf9-c9de56267426.png)
  
  