Make the tst ceiling the default in 21.3
This MR makes the TST ceiling approach the default in 21.3. It swaps out the
tstceil keyword for a
muonor keyword, which triggers the old behaviour. It also adds a container containing that result to the EDM, with the
tstceil result being written into the default container.
For now I just exchanged the old
tstceil chains with
muonor chains but there's a valid question over whether or not we really want to keep them.
This also includes a bugfix for the uninitialized variable problem in pufit that was noticed in master.
This should not be merged until after !28010 (merged) as I will have to recreate the references after that MR.