Fix find file breadcrumb styling

Closes #34427

app/assets/stylesheets/pages/projects.scss

@@ -377,6 +377,7 @@ a.deploy-project-label {
 }
 .breadcrumb.repo-breadcrumb {
+  flex: 1;
   padding: 0;
   background: transparent;
   border: none;

app/assets/stylesheets/pages/tree.scss

@@ -70,7 +70,8 @@
   }
   .file-finder {
-    width: 50%;
+    max-width: 500px;
+    width: 100%;
     .file-finder-input {
       width: 95%;