Fix Reactions Row Button vertical misalignment due to forced height

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

res/css/views/messages/_ReactionsRowButton.scss

@@ -16,7 +16,6 @@ limitations under the License.
 
 .mx_ReactionsRowButton {
     display: inline-flex;
-    height: 20px;
     line-height: $font-21px;
     margin-right: 6px;
     padding: 0 6px;