Merge branch 'cleanup/deprecate-to-true-false-type' into 'master'

Deprecate Dune::Std::to_true_type and to_false_type

See merge request !971 (merged)

(cherry picked from commit 1512e529)

f54750f5 [typetraits] Derive AlwaysTrue/False from std::true/false_type feaf3833 [std/typetraits] Deprecate Dune::Std::to_false/true_type. Use Dune::AlwaysFalse/True

enabled an automatic merge when the pipeline for 42d29448 succeeds

mentioned in commit 13c9ecb1

merged