Increase MAX_CACHED_PROCESSES config

For rationale, see: b/373735578#comment23

In performance testing, this improves performance on devices with
high RAM as they're able to reduce cold starts.
This regresses performance on low RAM devices because we spend
time freezing processes that we'll have to kill shortly anyway
due to LMK.
I'm seeing the same results consistently across a wide range of
form factors (phones, tablets, watches, TVs, automotive head
units).

Bug: 373735578
Bug: 374811976
Flag: EXEMPT config XML change
Change-Id: Id9c106151397796f75f67d87ff66d63efb5eb01d