Remove separator in SafetyCheck rows.

The separator is only needed if clicking on the left and the right of
the row does different things.

SafetyCheck not run:
before: http://screen/Ak3K7GEyxFsMEb6
after: http://screen/Gm8y5irTtwbh7Be
SafetyCheck run:
before: http://screen/5XUCb2MoLjMV38R
after: http://screen/BJmxvGDGpxtKWSZ

Bug: 1128564
Change-Id: Ib9c24395180b24a58f0feee2c8a2f9674578f00e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2426547Reviewed-by: Rainhard Findling <rainhard@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Xinghui Lu <xinghuilu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810448}

chrome/browser/resources/settings/safety_check_page/safety_check_child.html

@@ -44,7 +44,6 @@
     </div>
   </div>
   <template is="dom-if" if="[[showButton_(buttonLabel)]]" restamp>
-    <div class="separator"></div>
     <cr-button id="button" class$="[[buttonClass]]" on-click="onButtonClick_"
         aria-label="[[buttonAriaLabel]]" no-search>
       [[buttonLabel]]

chrome/browser/resources/settings/safety_check_page/safety_check_page.html

@@ -18,7 +18,6 @@
       </div>
       <template is="dom-if" if="[[shouldShowParentButton_(parentStatus_)]]"
           restamp>
-        <div class="separator"></div>
         <cr-button id="safetyCheckParentButton" class="action-button"
             on-click="onRunSafetyCheckClick_" no-search
             aria-label="$i18n{safetyCheckParentButtonAriaLabel}">
@@ -27,7 +26,6 @@
       </template>
       <template is="dom-if" if="[[shouldShowParentIconButton_(parentStatus_)]]"
           restamp>
-        <div class="separator"></div>
         <cr-icon-button id="safetyCheckParentIconButton"
             iron-icon="settings:refresh"
             on-click="onRunSafetyCheckClick_"