layout: THIS wedges Chrome during CSRF/API operation, geez

Firefox and Safari are unaffected.  No harm done in deleting a
pointer to a non-existing source map.  Oh my.

(cherry picked from commit 6a1ddbf7)

src/opnsense/www/themes/opnsense/build/css/bootstrap-select.css

@@ -279,4 +279,3 @@ span.form-control {
   width: 100%;
   float: none;
 }
-/*# sourceMappingURL=bootstrap-select.css.map */