Drop support for syslinux/isolinux

SYSLINUX has been abandoned for several years now, and it does not
even work with modern versions of the filesystems supported in kiwi.
This commit drops it and Fixes #2433

kiwi/bootloader/config/__init__.py

@@ -48,7 +48,6 @@ def new(
         name_map = {
             'grub2': {'grub2': 'BootLoaderConfigGrub2'},
             'grub2_s390x_emu': {'grub2': 'BootLoaderConfigGrub2'},
-            'isolinux': {'isolinux': 'BootLoaderConfigIsoLinux'},
             'systemd_boot': {'systemd_boot': 'BootLoaderSystemdBoot'}
         }
         try:

kiwi/bootloader/config/base.py

@@ -353,10 +353,7 @@ def get_install_image_boot_default(self, loader=None):
             log.warning('Switching to standard install')
             boot_id = 1
 
-        if loader and loader == 'isolinux':
-            return menu_list[boot_id].name
-        else:
-            return menu_list[boot_id].menu_id
+        return menu_list[boot_id].menu_id
 
     def get_boot_path(self, target='disk'):
         """
@@ -499,8 +496,6 @@ def get_gfxmode(self, target):
 
         if target == 'grub2':
             return gfxmode_map[gfxmode].grub2
-        elif target == 'isolinux':
-            return gfxmode_map[gfxmode].isolinux
         else:
             return gfxmode
 

kiwi/bootloader/config/grub2.py

@@ -936,7 +936,7 @@ def _setup_bios_image(self, mbrid, lookup_path=None):
                 os.sep.join(
                     [
                         self._get_bios_modules_path(lookup_path),
-                        Defaults.get_isolinux_bios_grub_loader()
+                        Defaults.get_iso_grub_loader()
                     ]
                 )
             ]