[a11y] Reduce tab stops for bluetooth page item

This CL removes unnecessary tab stops from the bluetooth-page element.
Secondary details that appear in the item viz. On/Off status are
already added in the button's aria description.

Tab stop for policy indicators were left as such since removing this
makes this detail inaccessible to some users.

Bug: 1025414
Change-Id: I40cc98b3871f7cc77a9252b05e39c669ebf12358
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1940813
Commit-Queue: Azeem Arshad <azeemarshad@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#722713}

chrome/browser/resources/settings/bluetooth_page/bluetooth_page.html

@@ -24,7 +24,7 @@
           <div id="bluetoothDevices" class="settings-box two-line no-padding">
             <div class="link-wrapper" actionable on-click="onTap_">
               <iron-icon icon="[[getIcon_(bluetoothToggleState_)]]"></iron-icon>
-              <div class="middle settings-box-text">
+              <div class="middle settings-box-text" aria-hidden="true">
                 $i18n{bluetoothPageTitle}
                 <div class="secondary" id="bluetoothSecondary">
                   [[getOnOffString_(bluetoothToggleState_,