Removed remaining references to old server handling code

src/ruby/lib/grpc.rb

@@ -47,5 +47,3 @@ begin
 ensure
   file.close
 end
-
-GRPC::Signals.wait_for_signals

src/ruby/lib/grpc/generic/active_call.rb

@@ -30,7 +30,6 @@
 require 'forwardable'
 require 'weakref'
 require_relative 'bidi_call'
-require_relative '../signals'
 
 class Struct
   # BatchResult is the struct returned by calls to call#start_batch.
@@ -123,10 +122,6 @@ module GRPC
       @unmarshal = unmarshal
       @metadata_tag = metadata_tag
       @op_notifier = nil
-      weak_self = WeakRef.new(self)
-      remove_handler = GRPC::Signals.register_handler(&weak_self
-                                                        .method(:cancel))
-      ObjectSpace.define_finalizer(self, remove_handler)
     end
 
     # output_metadata are provides access to hash that can be used to

src/ruby/lib/grpc/generic/rpc_server.rb

@@ -28,7 +28,6 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 require_relative '../grpc'
-require_relative '../signals'
 require_relative 'active_call'
 require_relative 'service'
 require 'thread'
@@ -353,10 +352,7 @@ module GRPC
         transition_running_state(:running)
         @run_cond.broadcast
       end
-      remove_signal_handler = GRPC::Signals.register_handler { stop }
       loop_handle_server_calls
-      # Remove signal handler when server stops
-      remove_signal_handler.call
     end
 
     alias_method :run_till_terminated, :run