Revert "Allow expected value to receive stub"

This reverts commit 6cd410c4c7.

Should not stub the method.
The end-user needs to do this.

src/spectator/expectations/expectation_partial.cr

@@ -25,7 +25,6 @@ module Spectator::Expectations
     end
 
     def to(stub : Mocks::MethodStub) : Nil
-      Mocks::Allow.new(@actual.value).to(stub)
       value = TestValue.new(stub.name, stub.to_s)
       matcher = if (arguments = stub.arguments?)
                   Matchers::ReceiveArgumentsMatcher.new(value, arguments)