disallow 32-bit *system* userspace on 6.2+

https://android-developers.googleblog.com/2022/09/optimize-for-android-go-lessons-from-google-apps-part-1.html



Year   Android   MinRAM
2017   8/O       512 MB
2018   9/P       512 MB
2019   10/Q      512 MB
2020   11/R      1 GB
2021   12/S      1 GB
2022   13/T      2 GB

More than 4GB (and really even ~3..3.5 GB) of ram basically
requires a 64-bit kernel, as no one wants to deal with
debugging PAE kernel complexities.

Devices newly launching on 2023's Android 14/U must use
a 64-bit kernel.  5.15 LTS is highest supported by T.
Hence 5.16+ must be a 64-bit kernel.
(see vts_kernel_isa_test.cpp)

Note:

This change doesn't take effect until 2024's Android 15/V,
and only then on the latest 6.~6 LTS, which will only be used
with the latest SoCs, and will thus only affect the latest
and thus premium devices (which likely have 10+ GB).
By the time these 6.6 using SoCs reach lower end devices,
it'll be 2026 or later, at which point I expect even
low end devices will have 4+GB.

Additionally note that technically this only affects
mainline using devices.  Non mainline usecases can
be customized (ie. for example this change reverted)
by oems/vendors however they wish.  Although we
won't be providing support (but considering the
existing state of 32-bit testing, that's already
pretty much the case).

Test: TreeHugger
Bug: 163141236
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I64f5db5a440465f0b48368815fea3029619a9681