MD Setting: drop changes to background-color on :hover

R=stevenjb@chromium.org
BUG=630067
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation
NOTRY=true  # android bots keep failing, this code doesn't even run on android...

Review-Url: https://codereview.chromium.org/2164223002
Cr-Commit-Position: refs/heads/master@{#407007}

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

@@ -19,10 +19,6 @@
         height: 34px;
       }
 
-      .user:hover {
-        background-color: #f0f0f0;
-      }
-
       .user-list {
         border: 1px solid gray;
         height: 160px;

chrome/browser/resources/settings/settings_root_css.html

@@ -31,7 +31,6 @@
       margin-top: 4px;
     };
     --settings-error-color: var(--paper-red-700);
-    --settings-hover-color: var(--google-grey-300);
 
     /* Some colors use non-MD colors.  These custom colors are specified by
      * UX design (bettes@). */

chrome/browser/resources/settings/settings_shared_css.html

@@ -79,11 +79,6 @@
         @apply(--settings-actionable);
       }
 
-      iron-dropdown .dropdown-content .dropdown-item:hover,
-      iron-dropdown .dropdown-content paper-item:hover {
-        background-color: var(--settings-hover-color);
-      }
-
       span ~ a {
         -webkit-margin-start: 4px;
       }