fix(frontends/lean/inductive_cmd): inductive datatype elaborator was 'fixing' parameter mismatches.

Given a datatype C with parameters As, if the declaration contained
(C Bs), the elaborator would silently replace it with (C As).

This bug would confuse users and make them believe they define something
different.
fix(frontends/lean/inductive_cmd): inductive datatype elaborator was 'fixing' parameter mismatches.