Allow Graph branch dropdown to expand to fit the width of the screen

app/views/projects/network/_head.html.haml

 .row-content-block.second-block.content-component-block.gl-px-0.gl-py-3
-  .gl-w-20
+  .gl-w-max-content.gl-max-w-full
     #js-graph-ref-switcher{ data: { project_id: @project.id, ref: @ref, network_path: project_network_path(@project) } }
 
   .oneline