grub.cfg: Remove grub.cfg in bootupd favor

- Bootupd used this file as a reference to generate static GRUB config
  files, the actual grub.cfg installed on the system comes from bootupd;
- Remove grub.cfg since this file is not used here anymore.

Signed-off-by: Renata Ravanelli <[email protected]>

Author: ravanelli

src/cosalib/cmdlib.py

@@ -447,9 +447,6 @@ def generate_image_json(srcfile):
     r = yaml.safe_load(open("/usr/lib/coreos-assembler/image-default.yaml"))
     for k, v in flatten_image_yaml(srcfile).items():
         r[k] = v
-    # Serialize our default GRUB config
-    with open("/usr/lib/coreos-assembler/grub.cfg") as f:
-        r['grub-script'] = f.read()
     return r