Remove invalid Namespace GraphQL type spec

spec/graphql/types/namespace_type.rb

@@ -5,7 +5,5 @@ require 'spec_helper'
 describe GitlabSchema.types['Namespace'] do
   it { expect(described_class.graphql_name).to eq('Namespace') }
 
-  it { expect(described_class).to have_graphql_field(:projects) }
-
   it { is_expected.to require_graphql_authorizations(:read_namespace) }
 end