Since we now use asciidoctor-tabs instead of spring-asciidoctor-backends,
we no longer need the `role="primary"` and `role="secondary"` attributes
for tab groups.
Closes gh-33506
This commit restructures the section on MockMvc so that the anchors
are easier to read. The standard integration has moved to a
Hamcrest Integration section at the same level as HtmlUnit Integration,
and a new AssertJ Integration section has been created.
Closes gh-32454
Sam Brannen