Remove unused CSS - loading indicator not needed in final solution

Author: Aditya

war/src/main/webapp/css/responsive-grid.css

@@ -1815,32 +1815,4 @@
 }
 @-ms-viewport {
   width: device-width;
-}
-/**
- * Loading indicator for POST buttons - Fix for JENKINS-76241
- */
-.jenkins-loading {
-  position: relative;
-  pointer-events: none;
-  opacity: 0.6;
-}
-
-.jenkins-loading::after {
-  content: "";
-  position: absolute;
-  top: 50%;
-  left: 50%;
-  width: 16px;
-  height: 16px;
-  margin: -8px 0 0 -8px;
-  border: 2px solid #fff;
-  border-radius: 50%;
-  border-top-color: transparent;
-  animation: jenkins-spin 0.6s linear infinite;
-}
-
-@keyframes jenkins-spin {
-  to {
-    transform: rotate(360deg);
-  }
-}
+}