Remove "redundant" begin block as per rubocop error

refs:
- http://www.rubydoc.info/gems/rubocop/0.27.0/RuboCop/Cop/Style/RedundantBegin
- https://travis-ci.org/test-kitchen/kitchen-google/jobs/248788163

lib/kitchen/driver/gce.rb

@@ -530,13 +530,11 @@ def wait_for_operation(operation)
       end
 
       def wait_for_server
-        begin
-          instance.transport.connection(state).wait_until_ready
-        rescue
-          error("Server not reachable. Destroying server...")
-          destroy(state)
-          raise
-        end
+        instance.transport.connection(state).wait_until_ready
+      rescue
+        error("Server not reachable. Destroying server...")
+        destroy(state)
+        raise
       end
 
       def zone_operation(operation_name)