Remove unnecessary "mac" meta data tag from Android Manifest

chrome/android/webapk/shell_apk/AndroidManifest.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2015 The Chromium Authors. All rights reserved.
      Use of this source code is governed by a BSD-style license that can be
      found in the LICENSE file.
 -->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="{{ manifest_package }}"
     android:versionCode="1"
     android:versionName="1.0" >
 
@@ skipping 13 matching lines @@
             </intent-filter>
             <intent-filter>
                 <action android:name="android.intent.action.VIEW"></action>
                 <category android:name="android.intent.category.DEFAULT"></category>
                 <category android:name="android.intent.category.BROWSABLE"></category>
                 <data android:scheme="https" android:host="{{ scope_url_host }}" android:pathPrefix=""></data>
             </intent-filter>
         </activity>
         <meta-data android:name="runtimeHost" android:value="{{ runtime_host }}" />
         <meta-data android:name="hostUrl" android:value="{{ host_url }}" />
-        <meta-data android:name="mac" android:value="{{ mac }}" />
         <meta-data android:name="scope" android:value="{{ scope_url }}" />
         <service
             android:name="org.chromium.webapk.shell_apk.WebApkServiceFactory"
             android:exported="true">
             <intent-filter>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.WEBAPK_API" />
             </intent-filter>
         </service>
     </application>
 </manifest>