This PR removes the temporary change we made to the yml test harness in #37285
to automatically set `include_type_name` to `true` in index creation requests
if it's not already specified. This is possible now that the vast majority of
index creation requests were updated to be typeless in #37611. A few additional
tests also needed updating here.
Additionally, this PR updates the test harness to set `include_type_name` to
`false` in index creation requests when communicating with 6.x nodes. This
mirrors the logic added in #37611 to allow for typeless document write requests
in test set-up code. With this update in place, we can remove many references
to `include_type_name: false` from the yml tests.
c2e9d13ebd