fix: Remove keyboard plugin

The used keyboard plugin brings us a few issues mainly this one:
when we open the keyboard and then close it, we couldn't scroll
anymore.

At the begining we use this keyboard for the auth page in order
to shrink the view and let a few buttons on top of the keyboard
on iOS. We created a PageLayout for that, and we need to use it
for cozy-auth (cozy/cozy-libs#872)

src/drive/targets/mobile/config.xml

@@ -111,7 +111,6 @@
     <plugin name="com-darryncampbell-cordova-plugin-intent" spec="^1.1.1" />
     <plugin name="com.lampa.startapp" spec="^0.1.4" />
     <plugin name="cordova-plugin-queries-schemes" spec="https://github.com/cozy/cordova-plugin-queries-schemes.git#f7cc50ec542d7eeab6857e366dceb2f039f5dcd9" />
-    <plugin name="cordova-plugin-keyboard" spec="https://github.com/cozy/cordova-plugin-keyboard.git#4fa4850e6f0ea78e1e2ce573ccde5531a2353edb" />
     <plugin name="cordova-plugin-file-opener2" spec="^2.2.0">
         <variable name="ANDROID_SUPPORT_V4_VERSION" value="27.+" />
     </plugin>