[files-progress] Fix progress indicator icon width.

The other elements in the panel push icon to the right so it shrinks.
Changing to min-width to fix it.

Bug: 1133113
Change-Id: I9f2cfbbaf0bb111b3b80cd4a685effba08f720a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2437652Reviewed-by: Alex Danilo <adanilo@chromium.org>
Commit-Queue: Omid Tourzan <oto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811574}

ui/file_manager/file_manager/foreground/elements/xf_panel_item.js

@@ -200,12 +200,12 @@ class PanelItem extends HTMLElement {
 
               :host([detailed-summary][data-category='collapsed']) #indicator {
                   margin-inline-end: 20px;
-                  width: 28px;
+                  min-width: 28px;
               }
 
               :host([detailed-summary][data-category='expanded']) #indicator {
                   margin-inline-end: 18px;
-                  width: 32px;
+                  min-width: 32px;
               }
 
               :host([detailed-summary]) #primary-action {