Introduce shred_final_overwrite_with_zeros, a new configuration option
to control whether devices will receive a final overwrite with zeros
during cleaning. Additionally, rename erase_devices_iterations to
shred_random_overwrite_iterations to clarify the true meaning of this
configuration option.
Also, ensure a warning is raised in the logs to raise awareness around
the potential security risk of running cleaning with iterations=0 and
overwrite_with_zeros=False.
Change-Id: I0dd3f488ab2cd0df778f34a5a23948fa0c6c4334
Closes-Bug: #1568811
Depends-On: I7053034f5b5bc6737b535ee601e6fb71284d4a83