Settings: Fix typo in Polymer's data bindings causing search errors.

Typos (missing "]" bracket)  were introduced at r709022 and r709160.

Bug: 1019576
Change-Id: I0950c8f466f5a1a825cb92435ba969585bedce71
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890502
Auto-Submit: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711000}

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

@@ -150,7 +150,7 @@
 
       <template is="dom-if" route-path="/syncSetup">
         <settings-subpage
-            associated-control="[[$$('#sync-setup')]"
+            associated-control="[[$$('#sync-setup')]]"
             page-title="$i18n{syncPageTitle}"
             learn-more-url="$i18n{syncAndGoogleServicesLearnMoreURL}">
           <settings-sync-page

chrome/browser/resources/settings/people_page/people_page.html

@@ -261,7 +261,7 @@
       </div>
       <template is="dom-if" route-path="/syncSetup">
         <settings-subpage
-            associated-control="[[$$('#sync-setup')]"
+            associated-control="[[$$('#sync-setup')]]"
             page-title="$i18n{syncPageTitle}"
             learn-more-url="$i18n{syncAndGoogleServicesLearnMoreURL}">
           <settings-sync-page