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.