The desired mode of operation to attempt to use when
performing a reset.
When set to hauNever(1) a high-availability upgrade
will never be performed. Instead a standard upgrade
will be performed.
When set to hauIfPossible(2) a high-availability upgrade
will be performed if the current and target images are
compatible, otherwise a standard upgrade will be performed.
When set to hauAlways(3) a high-availability upgrade
will always be performed. If the current and target
images are incompatible then no upgrade will occur.