Remove "instructions" row in CSV type tempvars

Removed the “instructions” box that previously appeared when choosing
CSV type tempvars. It is safe to assume that users know the format, and
the real estate gain makes this change very worth it

ui/src/dashboards/components/TemplateQueryBuilder.js

@@ -16,7 +16,7 @@ const TemplateQueryBuilder = ({
 }) => {
   switch (selectedType) {
     case 'csv':
-      return <div className="tvm-csv-instructions">Enter values below</div>
+      return null
     case 'databases':
       return <div className="tvm-query-builder--text">SHOW DATABASES</div>
     case 'measurements':

ui/src/style/components/template-variables-manager.scss

@@ -108,6 +108,7 @@ $tvmp-table-gutter: 8px;
   border-radius: $radius;
   border: 2px solid $g5-pepper;
   background-color: $g2-kevlar;
+  overflow: hidden;
   transition:
     border-color 0.25s ease;