Unit test about WP_Comment_Query and multiple post_type needs update

[kouratoras]

During the implementation of #35512, I found out that a unit test function of #20006 ticket needs update, as it uses 3 custom post types, but registers/unregisters only 2 of them.

[kouratoras]

Unit test update

[boonebgorges]

Thanks!

[boonebgorges]

In 36415:

Fix set up/tear down of post types in comment query test.

Introduced in [31015].

Props kouratoras.
Fixes #35633.