[Bluetooth] Use secondary text color for device connectivity status.

As per recommendation in Comment #30 of crbug.com/1114876. This
is the same grey used in Network Settings secondary text.

Bug: b:167556640
Change-Id: I5a669cae3e43fc7cfe3d57eb276a4f6584a322e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2404141
Auto-Submit: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: James Vecore <vecore@google.com>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805877}

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

@@ -17,7 +17,7 @@
       }
 
       .state[connected] {
-        color: var(--google-green-500);
+        color: var(--cr-secondary-text-color);
       }
     </style>
     <div focus-row-container>