style: SIP-34 labels (#10403)

* style: SIP-34 labels

Aligning with SIP-34 designs for labels/pills. Going uppercase fixes the
padding issues we had before, and the rounder pills look better.

Cleaning up some CSS in the process

* lint

superset-frontend/src/explore/components/ExploreChartHeader.jsx

@@ -163,7 +163,6 @@ export class ExploreChartHeader extends React.PureComponent {
             endTime={chartUpdateEndTime}
             isRunning={chartStatus === 'loading'}
             status={CHART_STATUS_MAP[chartStatus]}
-            style={{ fontSize: '10px', marginRight: '5px' }}
           />
           <ExploreActionButtons
             actions={this.props.actions}