Remove empty navigation stop on OS Settings page

Mark the tooltip as aria-hidden since it is read as the description for
the dropdown.

Bug: 1024004
Change-Id: I23ee342ce23275a805d7ab46c40a5ae3fc5b867a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1913082
Auto-Submit: Bailey Berro <baileyberro@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Bailey Berro <baileyberro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714775}

chrome/browser/resources/settings/chromeos/os_search_page/os_search_page.html

@@ -59,7 +59,7 @@
                   aria-label="$i18n{osSearchEngineTooltip}"
                   aria-describedby="tooltip"></iron-icon>
               <paper-tooltip id="tooltip" for="help-icon" position="bottom"
-                  fit-to-visible-bounds>
+                  aria-hidden="true" fit-to-visible-bounds>
                 $i18n{osSearchEngineTooltip}
               </paper-tooltip>
             </div>