Revert "Merge branch 'janno/tc-opaque-unseal' into 'master'"

This reverts merge request !487 (merged). It broke the Iris build:

File "./iris/base_logic/lib/ghost_var.v", line 119, characters 9-32:
Error: Could not fill dependent hole in "apply"

File "./iris/base_logic/lib/gen_heap.v", line 194, characters 9-32:
Error: Could not fill dependent hole in "apply"