Remove explicit sudoers requirement.

Most of our build process runs as root and the overhead of explicitly
tracking sudo commands in the shipped sudoers.d file, plus the
operational overhead of keeping the sudoers.d file updated on build
hosts over time, is now considered to be unnecessary.
Instead, we now document that the build process will expect sudo
commands to work and the operator must make this happen (either by
running as root, via sudo -E, or allowing passwordless sudo for the
build user).

Change-Id: If2628e7d0c7efde0fb99c84a217523ba29b1b38d
Merge "Remove explicit sudoers requirement."