Add tablespace handling to cache-manager.sh

The cache-manager was missing PostgreSQL tablespace handling, causing HAF
caches to be incomplete (6.9GB instead of ~20GB with empty tablespace).

Changes:
- Add _fix_pg_tblspc_symlinks() to fix absolute symlinks after extraction
- Add _convert_pg_tblspc_to_relative() to convert symlinks before caching
- Update _relax_pgdata_permissions() to handle tablespace directory
- Update _restore_pgdata_permissions() to handle tablespace directory

PostgreSQL uses pg_tblspc/ symlinks with absolute container paths that
become invalid when data is extracted elsewhere. Converting to relative
paths (../../tablespace) ensures symlinks work in any location.