Fix Clone project button in dark mode

app/assets/stylesheets/pages/projects.scss

@@ -548,15 +548,6 @@ pre.light-well {
   }
 }
 
-.git-clone-holder,
-.mobile-git-clone {
-  .btn {
-    .icon {
-      fill: $white;
-    }
-  }
-}
-
 .new-protected-branch,
 .new-protected-tag {
   label {

app/assets/stylesheets/pages/tree.scss

@@ -6,10 +6,6 @@
   .nav-block {
     margin: 16px 0;
 
-    .btn svg {
-      color: $gl-text-color-secondary;
-    }
-
     .tree-ref-holder {
       margin-right: 15px;
     }