Revert^2 "Boot VM without bootloader - using init ramdisk"

Remove ABL from the boot flow of VMs. Virtualization service uses
microdroid.json to construct the appropriate vm_config.

Partitions:
1. Boot related partitions (boot/init_boot/vendor_boot) are no more
   required. kernel & init ramdisk is directly passed via crosvm command
   line.
2. uboot_env is obsolete without ABL
3. bootconfig partition is no more required because we are attaching the
   bootconfigs to initrd image.

This reverts commit 0f71596bd5333f08d07ed33dbb5425390dd8aa79

Bug: 240235424
Test: atest MicrodroidTestCase
Change-Id: I1b4c3ec792db9898093c4ccd3c037657c50a934f
diff --git a/microdroid/Android.bp b/microdroid/Android.bp
index 7b28ad2..1a9a217 100644
--- a/microdroid/Android.bp
+++ b/microdroid/Android.bp
@@ -573,3 +573,32 @@
     name: "microdroid_bootconfig_normal_src",
     srcs: ["bootconfig.normal"],
 }
+
+prebuilt_etc {
+    name: "microdroid_kernel_unsigned",
+    src: "empty_kernel",
+    filename: "microdroid_kernel_unsigned",
+    arch: {
+        arm64: {
+            src: ":microdroid_kernel_prebuilts-5.15-arm64",
+        },
+        x86_64: {
+            src: ":microdroid_kernel_prebuilts-5.15-x86_64",
+        },
+    },
+}
+
+avb_add_hash_footer {
+    name: "microdroid_kernel_signed",
+    src: ":microdroid_kernel_unsigned",
+    filename: "microdroid_kernel",
+    partition_name: "bootloader",
+    private_key: ":microdroid_sign_key",
+    salt: bootloader_salt,
+}
+
+prebuilt_etc {
+    name: "microdroid_kernel",
+    src: ":microdroid_kernel_signed",
+    relative_install_path: "fs",
+}
diff --git a/microdroid/microdroid.json b/microdroid/microdroid.json
index f02dcbf..00cedc8 100644
--- a/microdroid/microdroid.json
+++ b/microdroid/microdroid.json
@@ -1,21 +1,9 @@
 {
-  "bootloader": "/apex/com.android.virt/etc/fs/microdroid_bootloader",
+  "kernel": "/apex/com.android.virt/etc/fs/microdroid_kernel",
   "disks": [
     {
       "partitions": [
         {
-          "label": "boot_a",
-          "path": "/apex/com.android.virt/etc/fs/microdroid_boot.img"
-        },
-        {
-          "label": "init_boot_a",
-          "path": "/apex/com.android.virt/etc/fs/microdroid_init_boot.img"
-        },
-        {
-          "label": "vendor_boot_a",
-          "path": "/apex/com.android.virt/etc/fs/microdroid_vendor_boot.img"
-        },
-        {
           "label": "vbmeta_a",
           "path": "/apex/com.android.virt/etc/fs/microdroid_vbmeta.img"
         },
@@ -25,16 +13,6 @@
         }
       ],
       "writable": false
-    },
-    {
-      "partitions": [
-        {
-          "label": "uboot_env",
-          "path": "/apex/com.android.virt/etc/fs/uboot_env.img",
-          "writable": false
-        }
-      ],
-      "writable": true
     }
   ],
   "memory_mib": 256,