test: update postmortem metadata test for V8 7.7

The following metadata has changed:

- v8dbg_class_ConsString__first__String
  - Class is now generated via torque.
  - Postmortem tools should use v8dbg_class_ConsString__first_offset__int
  - Refs: https://github.com/v8/v8/commit/14274bb16afbdd33baef3274298bb32e1a65a3b9

- v8dbg_class_ConsString__second__String
  - Class is now generated via torque.
  - Postmortem tools should use v8dbg_class_ConsString__second_offset__int
  - Refs: https://github.com/v8/v8/commit/14274bb16afbdd33baef3274298bb32e1a65a3b9

- v8dbg_class_SlicedString__offset__SMI
  - Class is now generated via torque.
  - Postmortem tools should use v8dbg_class_SlicedString__offset_offset__int
  - Refs: https://github.com/v8/v8/commit/14274bb16afbdd33baef3274298bb32e1a65a3b9

- v8dbg_class_ThinString__actual__String
  - Class is now generated via torque.
  - Postmortem tools should use v8dbg_class_ThinString__actual_offset__int
  - Refs: https://github.com/v8/v8/commit/14274bb16afbdd33baef3274298bb32e1a65a3b9

PR-URL: https://github.com/nodejs/node/pull/28918


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>