feat: add new vaccine candidates chart with FDA approval filter and update dashboard configuration

- Add new pie chart "Vaccine Candidates per Phase" (ID 163) with FDA approved indications filter
- Update existing chart 121 query context configuration
- Set dashboard slug to "covid" and add new chart to dashboard layout
- Clean up dashboard metadata by removing unused color scheme configurations

charts/Vaccine_Candidates_per_Phase_121.yaml

@@ -28,7 +28,9 @@ params:
   url_params: {}
   viz_type: pie
   annotation_layers: []
-query_context: null
+query_context: '{"datasource":{"id":13,"type":"table"},"force":false,"queries":[{"time_range":"No
+  filter","filters":[],"extras":{"having":"","where":""},"applied_time_extras":{},"columns":["clinical_stage"],"metrics":["count"],"annotation_layers":[],"row_limit":10000,"series_limit":0,"group_others_when_limit_reached":false,"order_desc":true,"url_params":{},"custom_params":{},"custom_form_data":{},"post_processing":[{"operation":"contribution","options":{"columns":["count"],"rename_columns":["count__contribution"]}}]}],"form_data":{"adhoc_filters":[],"annotation_layers":[],"color_scheme":"supersetColors","datasource":"13__table","donut":true,"groupby":["clinical_stage"],"innerRadius":44,"label_line":true,"label_type":"key","labels_outside":true,"metric":"count","number_format":"SMART_NUMBER","outerRadius":61,"queryFields":{"groupby":"groupby","metric":"metrics"},"row_limit":10000,"show_labels":true,"show_legend":false,"slice_id":121,"time_range":"No
+  filter","url_params":{},"viz_type":"pie","force":false,"result_format":"json","result_type":"full"},"result_format":"json","result_type":"full"}'
 cache_timeout: null
 uuid: 30b73c65-85e7-455f-bb24-801bb0cdc670
 version: 1.0.0