Enables some incorrectly disabled tests

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

@@ -203,7 +203,7 @@ module GRPC
       end
 
       # Asserts that the appropriate methods are defined for each added rpc
-      # spec. Is intended to aid verifying that serve2Ar classes are correctly
+      # spec. Is intended to aid verifying that server classes are correctly
       # implemented.
       def assert_rpc_descs_have_methods
         rpc_descs.each_pair do |m, spec|

src/ruby/spec/generic/active_call_spec.rb

@@ -67,7 +67,7 @@ describe GRPC::ActiveCall do
     end
 
     describe '#multi_req_view' do
-      xit 'exposes a fixed subset of the ActiveCall methods' do
+      it 'exposes a fixed subset of the ActiveCall methods' do
         want = %w(cancelled, deadline, each_remote_read, metadata, shutdown)
         v = @client_call.multi_req_view
         want.each do |w|
@@ -77,7 +77,7 @@ describe GRPC::ActiveCall do
     end
 
     describe '#single_req_view' do
-      xit 'exposes a fixed subset of the ActiveCall methods' do
+      it 'exposes a fixed subset of the ActiveCall methods' do
         want = %w(cancelled, deadline, metadata, shutdown)
         v = @client_call.single_req_view
         want.each do |w|