revert modal z-index and lower the footer z-index instead

shell/assets/styles/base/_variables.scss

@@ -39,14 +39,16 @@ $z-indexes: (
 
   mainHeader: 14,
 
+  cruFooter: 19,
+
+  modalOverlay: 20,
+  modalContent: 21,
+
   tooltip: 30,
 
   dropdownOverlay: 40,
   dropdownContent: 41,
 
-  modalOverlay: 42,
-  modalContent: 43,
-
   loadingMain: 51
 );
 

shell/components/CruResourceFooter.vue

@@ -117,7 +117,7 @@ export default {
   display: flex;
   justify-content: flex-end;
   margin-top: 20px;
-  z-index: 40;
+  z-index: z-index('cruFooter');
 
   .btn {
     margin-left: 20px;