llkd: moved from optional to required component

The Live Lock Killer Daemon (llkd) has provided enough hero moments to
improve system stability, by providing actionable collection of data
to resolve kernel, and some user space, misbehaviors.  It is time to
move llkd to a required component.

NB: For llkd to be effective at finding real kernel live lock
conditions, system requirements are that there are no more un-waited
for Zombie processes, and that no kernel drivers use indeterminate
periods of uninterruptible sleep.  Any kernel and user space tasks
that are killed because of suspicious behavior, must themselves have
a benefactor to restart them if necessary.  If a true live lock is
discovered, data will be collected and the kernel will be panic'd to
recover from the situation.

Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 164946924
Test: llkd is ever present on a release build.
Change-Id: I986a8545252bc5b68d09a6a0f4f506a58998c8a0