Render deprecation correctly for arguments

Arguments do not get the :is_deprecated flag set correctly by the library. We need to work around that.

The following discussion from !57720 (merged) should be addressed:

• @pedropombeiro started a discussion:

  note: I reached out to #f_graphql as I believe we should get a **{warning-solid}** icon next to the field name (example MR), but bundle exec rake gitlab:graphql:update_all is not creating it.