MDL-55071 theme_boost: remove empty blocks in scss

Part of MDL-55071

theme/boost/scss/moodle/admin.scss

@@ -540,15 +540,6 @@
                 font-size: $font-size-sm;
                 @extend .text-muted;
             }
-
-            .release {
-            }
-        }
-
-        .availability {
-        }
-
-        .settings {
         }
 
         .uninstall {

theme/boost/scss/moodle/backup-restore.scss

@@ -45,9 +45,6 @@
     color: inherit;
 }
 
-.path-backup .backup_progress .backup_stage.backup_stage_next {
-}
-
 .path-backup .backup_progress span.backup_stage.backup_stage_complete {
     color: inherit;
 }

theme/boost/scss/moodle/modules.scss

@@ -463,9 +463,6 @@ div#dock {
 
                     @include box-shadow(0 5px 10px rgba(0, 0, 0, 0.2));
                 }
-
-                &:hover .toggle-display {
-                }
             }
         }
     }