During route activation, a componentless route will not have a context created
for it, but the logic continues to recurse so that children are still
activated. This can be seen here:
362f45c4bf/packages/router/src/operators/activate_routes.ts (L151-L158)
The current deactivation logic does not currently account for componentless routes.
This commit adjusts the deactivation logic so that if a context cannot
be retrieved for a given route (because it is componentless), we
continue to recurse and deactivate the children using the same
`parentContexts` in the same way that activation does.
Fixes#20694
PR Close#40196