Apply theme to half sheet and clean up

https://screenshot.googleplex.com/67T5pt8gK7hLG4C

Test: Screenshot
Bug: 196262706
Change-Id: Ia4d55f7dfff49993222ac3627851ab89279b51d0
diff --git a/nearby/halfsheet/res/values/strings.xml b/nearby/halfsheet/res/values/strings.xml
index a3a2b00..12e3c23 100644
--- a/nearby/halfsheet/res/values/strings.xml
+++ b/nearby/halfsheet/res/values/strings.xml
@@ -15,7 +15,7 @@
   -->
 
 <resources>
-    <string name="app_name">Nearby HalfSheet Dialog</string>
+
     <string name="common_done" description="After pairing process finish button text to dismiss halfsheet">Done</string>
     <string name="common_save">Save</string>
     <string name="common_connect" description="Button text to start connecting process">Connect</string>