libc: minimal: remove deprecated Kconfigs

The following Kconfigs have been deprecated for more than 2
releases, remove them:

- `CONFIG_SUPPORT_MINIMAL_LIBC`
- `CONFIG_MINIMAL_LIBC_MALLOC`
- `CONFIG_MINIMAL_LIBC_CALLOC`
- `CONFIG_MINIMAL_LIBC_REALLOCARRAY`

Signed-off-by: Yong Cong Sin <ycsin@meta.com>