test: update postmortem metadata test

This commit updates the following postmortem metadata constants:

- v8dbg_class_Map__inobject_properties_or_constructor_function_index__int
  - This is now
    v8dbg_class_Map__inobject_properties_start_or_constructor_function_index__char
    as of
    https://github.com/v8/v8/commit/61bf2cc69217a4e9c7a40bb74269508fa26c2062
- v8dbg_class_Map__instance_attributes__int
  - This is now v8dbg_class_Map__instance_type__uint16_t as of
    https://github.com/v8/v8/commit/c00bb6da1cef9f7e9dab842904232255717f8291
    and
    https://github.com/v8/v8/commit/cb46310a799eb0d60a613ead0af8c8200c5338b1
- v8dbg_class_Map__instance_size__int
  - This is now v8dbg_class_Map__instance_size_in_words__char as of
    https://github.com/v8/v8/commit/61bf2cc69217a4e9c7a40bb74269508fa26c2062

Refs: https://github.com/nodejs/node-v8/pull/34

PR-URL: https://github.com/nodejs/node/pull/17489


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>