Use the standard class name for dumpable keys

Class names are guaranteed to be both non-null and unique, whereas
canonical names may be null for certain types. This avoids issues
where the validity of such names might depend on bytecode optimizations.

Bug: 309672095
Test: m + presubmit
Flag: EXEMPT bugfix
Change-Id: Ie80bdc0a056d5bfc27e1b9d88c43fc5a561d2648