[tests.elliptic-swipdg-discretization] make it work again
* update space, operator, products
* update assembler
* disable EstimatorStudy for the moment
* add override and final keywords
* update expected L2 and H1 errors (got slightly worse)
[tests.elliptic-discretizations] reenabled swipdg
[tests.stuff-la-solver] reenable SWIPDG