Closes mozilla-mobile#1563: Update Google search code

Author: sblatz

components/browser/search/src/main/assets/searchplugins/google-2018.xml

@@ -11,7 +11,7 @@
   <Param name="q" value="{searchTerms}"/>
   <Param name="ie" value="utf-8"/>
   <Param name="oe" value="utf-8"/>
-  <Param name="client" value="firefox-b-1"/>
+  <Param name="client" value="firefox-b-1-m"/>
 </Url>
 <SearchForm>https://www.google.com</SearchForm>
 </SearchPlugin>

components/browser/search/src/main/assets/searchplugins/google.xml

@@ -11,7 +11,7 @@
   <Param name="q" value="{searchTerms}"/>
   <Param name="ie" value="utf-8"/>
   <Param name="oe" value="utf-8"/>
-  <Param name="client" value="firefox-b"/>
+  <Param name="client" value="firefox-b-m"/>
 </Url>
 <SearchForm>https://www.google.com</SearchForm>
 </SearchPlugin>