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: If68ff67be69770003133a31590eaff3c4a44bf06