Queried object and Query vars are not consistent when querying two custom taxonomies

[Chouby]

The queried object returns the first queried taxonomy (as expected) while the query vars $query->query_vars['taxonomy'] and $query->query_vars['term'] are unexpectedly related to the last queried taxonomy.

[boonebgorges]

Good catch. It looks like query_vars used to be set to the first one, but I accidentally changed it in [29891].

[boonebgorges]

In 36484:

WP_Query taxonomy query vars should be set to first of multiple taxonomies.

This provides better parity with get_queried_object(), which will return the
first taxonomy/term matched by the current query.

[29891] introduced the abnormal behavior for the 'taxonomy' and 'term'
query vars.

Props Chouby.
Fixes #35619.