Bug 32925: Use a new state for this message

Bug 32925: Use a new state for this message

The previous patch didn't work, there is a validation step that make the
form non-accessible after it's greyed out.

This patch is using a new state is_submitting, like the other messages.

Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit daeccd0b8c2ae9e3d16f32db379a39994433b69d)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>