[Sync EN] Fix ssh2_sftp_* return types to include false (realpath, readlink, stat, lstat)

PR: `https://github.com/php/doc-en/pull/5640` (2026-06-29)

**Файлы RU для обновления**
- `reference/ssh2/functions/ssh2-sftp-lstat.xml`
- `reference/ssh2/functions/ssh2-sftp-readlink.xml`
- `reference/ssh2/functions/ssh2-sftp-realpath.xml`
- `reference/ssh2/functions/ssh2-sftp-stat.xml`

