[VisBuilder] Add TODOs with issue links, fix test ID

Restores previous test ID for count field button

Signed-off-by: Josh Romero <[email protected]>

src/plugins/vis_builder/public/application/components/data_tab/field.tsx

@@ -65,6 +65,7 @@ export const Field = ({ field, getDetails }: FieldProps) => {
       closePopover={() => setOpen(false)}
       anchorPosition="rightUp"
       panelClassName="vbItem__fieldPopoverPanel"
+      // TODO: make reposition on scroll actually work: https://github.com/opensearch-project/OpenSearch-Dashboards/issues/2782
       repositionOnScroll
       data-test-subj="field-popover"
     >

src/plugins/vis_builder/public/application/components/data_tab/field_selector.tsx

@@ -26,6 +26,7 @@ interface IFieldCategories {
 export const FieldSelector = () => {
   const indexPattern = useIndexPatterns().selected;
   const fieldSearchValue = useTypedSelector((state) => state.visualization.searchField);
+  // TODO: instead of a single fetch of sampled hits for all fields, we should just use the agg service to get top hits or terms per field: https://github.com/opensearch-project/OpenSearch-Dashboards/issues/2780
   const hits = useSampleHits();
   const [filteredFields, setFilteredFields] = useState<IndexPatternField[]>([]);
 
@@ -77,6 +78,8 @@ export const FieldSelector = () => {
         <DraggableFieldButton
           field={{ name: 'count', displayName: 'Count', type: 'number' }}
           dragValue={COUNT_FIELD}
+          // TODO: improve the test ID for the Count field (or use a non-conflicting `name` value) and update functional test accordingly: https://github.com/opensearch-project/opensearch-dashboards-functional-test/blob/6f4125c9823f8e54e138076737ca16f011cbd7e7/cypress/integration/core-opensearch-dashboards/opensearch-dashboards/apps/vis_builder/vis_types/metric.spec.js#L36
+          dataTestSubj="field-undefined-showDetails"
         />
         <FieldGroup
           id="categoricalFields"