Revert "query: allow _make_writable on query handlers"

Revert "query: allow _make_writable on query handlers"

This reverts commit cf4fbc005c5c530c2a509a943a05b91d6c9af3fb.

This change did not improve the situation for bindings because
queries are usually created, then directly passed to a function
and not stored elsewhere, and the writability problem with
miniobjects usually happens with buffers or caps instead.