Documentation/mm/page_owner.rst: delete frequently changing experimental data

Documentation/mm/page_owner.rst: delete frequently changing experimental data

The kernel size changes due to many factors, such as compiler
version, configuration, and the build environment. This makes
size comparison figures irrelevant to reader's setup.

Remove these figures and describe the effects of page owner
to the kernel size in general instead.

Thanks for Jonathan Corbet, Bagas Sanjaya and Mike Rapoport's
constructive suggestions.

Signed-off-by: Yixuan Cao <caoyixuan2019@email.szu.edu.cn>
Link: https://lore.kernel.org/r/20221005145525.10359-1-caoyixuan2019@email.szu.edu.cn
Signed-off-by: Jonathan Corbet <corbet@lwn.net>