fix(Role Portlet): Make the view roles sidebar scrollable (#31017)

This pull request includes changes to the
`core-web/libs/dotcms-scss/jsp/scss/backend/dot-admin/portlets/_view-roles.scss`
file to improve the layout and usability of the roles view in the admin
portlet. The most important changes include adding overflow handling and
adjusting the height and padding of elements.

Layout improvements:

* Added `overflow: auto` to `.view-roles` and `.view-roles
.portlet-sidebar` to handle content overflow.
* Changed the height of `.view-roles__tree` from `100%` to `auto` and
added padding at the bottom for better spacing.

### Video

https://github.com/user-attachments/assets/db0d5412-90ec-407d-8735-2d9e12e00bbc

core-web/libs/dotcms-scss/jsp/scss/backend/dot-admin/portlets/_view-roles.scss

@@ -1,6 +1,7 @@
 .view-roles,
 .view-roles .portlet-sidebar {
     height: 100%;
+    overflow: auto;
 }
 
 .view-roles {
@@ -31,7 +32,8 @@
 }
 
 .view-roles__tree {
-    height: 100%;
+    height: auto;
+    padding-bottom: $spacing-2;
 }
 
 .view-roles__tabs,