Remove embedded.mk

The common mk files form a long chain of generic sounding names that
don't make much sense. For instance, embedded, base, core_minimal, core
and core_base all inherit each other, but there's no logical ordering
of these names.

The common mks will be split based on destination partition, which will
create many new files. Merging some of the common ones before this split
keeps the total number of mks under control.

There are only 2 products inheriting this mk excluding base.mk (which
has over 300 descendants). The other levels in the hierarchy all have
multiple device categories rooted at them (e.g. wearables from base.mk,
tvs and cars from core_minimal.mk), but embedded.mk has not which
makes it a compelling target to remove.

Bug: 80410283
Test: diff products variables with multiproduct_kati
Change-Id: I35c05973dfefefb7a31686476215386b8b89a557
Merged-In: I35c05973dfefefb7a31686476215386b8b89a557
Merged-In: I2e25032645c87f084f911e14fade16bc802ff457