kleaf: abi: Stop injecting base symbols

Previously, `extract_symbols.py` unconditionally injected
`module_layout`, `__put_task_struct`, and `utf8_data_table` into
generated symbol lists. This caused a DRY violation, as these symbols
are already tracked in the static base symbol list (e.g.,
gki/aarch64/symbols/base).

This change removes the `_ALWAYS_INCLUDED` hardcoded injection from
`extract_symbols.py`.

Bug: 523219327
Test: TH
Change-Id: I15bf444b9ae1b723d594d41119d88cd719d8ef9c