Fix password leak from ProcessExecution errors

This backport required changes to fix both issues:
* Make execute method clean password in exception
* Make sure mask_password works properly

This backport is not trivial as these fixes relies on many other
changes, only the necessary code have been imported/adapted.

------------------------------------------------
The sync pulls in the following changes (newest to oldest):

63c99a0f - Mask passwords in exceptions and error messages
66142c34 - Make strutils.mask_password more secure
d6b55fb2 - Remove `processutils` dependency on `log`
cb5a804b - Move `mask_password` to strutils

-----------------------------------------------

Closes-Bug: 1343604
Closes-Bug: 1345233
SecurityImpact

Change-Id: I3b49b1d667f6ade9ae3f6765d735440a3e838917