SpringBoot Test that server.max-http-header-size is applied when using HTTP/2

Forward port of issue #31329 to 3.0.x.

Comment From: wilkinsona

This isn't needed in 3.0.x due to these changes in Tomcat 10 which mean that the Http2Protocol uses the underlying HTTP 1.1 protocol's max header size. We can keep the new tests to verify that this is the case.