fix getType on object/distinct types giving bare generic sym

[metagn]

fixes #24503, refs #22655, alternative to #24509

This removes the need for the fix in #22655 entirely, since getType no longer gives nodes with invalid tyGenericBody types for types that are actually instantiated. But it significantly changes the output of getType, and likely not in a great way. Maybe an inst=true version of t.typeInst would be better, but this also changes the output, and t.typeInst was only fixed recently for types without generic fields in #24425 (also the dereferenced types of generic ref objects still give the ref object type as the typeInst).

There is also this line that has a similar issue, but it doesn't seem to be encountered, likely because skipped tyGenericInst types aren't very common when using getTypeInst.

Alternatively we could still produce a sym node but just set its type to the current type, i.e. result = atomicType(t.sym); result.typ = t. Edit: Done in #24511 just to test