Add --os_version and --os_patch_level to bootimg

These flags were passed in make but not soong.

Also remove the ramdisk from boot.img because it actually wasn't
supposed to be used there, the ramdisk is used in init_boot.img.

Bug: 377562951
Test: Presubmits
Change-Id: I0391241d4b956788f855541684814bcf29614cb8