Setup flag for multiple MaxActivationDepths

We will add treatment arms for all different values of
MaxActivationDepth instead of only per-pid (3).

This will be reverted after the memcg v2 experiment is complete, and
before the final 25Q2 TOT snap. The final MaxActivationDepth value will
be commited to cgroups.json on AOSP. go/android-memcgv2-exp

Bug: 384577842
Test: setprop persist.device_config.mglru_native.lru_gen_config core_and_mm_walk
Test: setprop persist.device_config.mglru_native.lru_gen_config core_and_nonleaf_young
Test: setprop persist.device_config.mglru_native.lru_gen_config all
Test: find /sys/fs/cgroup/ -name cgroup.controllers -exec grep -q memory {} \; -print (after each of above)
Ignore-AOSP-First: 25Q2 Beta Experiment only go/android-memcgv2-exp
Change-Id: I243bd8fe51f0122bec640f06c8c28b5426ecfd8b