Add BuildBucket manifest scheduling support.

scripts/slave/recipes/cros/cbuildbot.expected/chromiumos_paladin_buildbucket.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--spec",
       "cache_dir = '[GIT_CACHE]'\nsolutions = [{'deps_file': '.DEPS.git', 'managed': True, 'name': 'chromite', 'url': 'https://chromium.googlesource.com/chromiumos/chromite.git'}]",
       "--patch_root",
       "chromite",
@@ skipping 23 matching lines @@
       "@@@STEP_LOG_LINE@json.output@  \"patch_root\": \"chromite\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"properties\": {}, @@@",
       "@@@STEP_LOG_LINE@json.output@  \"root\": \"chromite\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"step_text\": \"Some step text\"@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
-      "git",
-      "checkout",
-      "master"
-    ],
-    "cwd": "[SLAVE_BUILD]/chromite",
-    "name": "checkout chromite branch [master]"
-  },
-  {
-    "cmd": [
-      "git",
-      "pull"
-    ],
-    "cwd": "[SLAVE_BUILD]/chromite",
-    "name": "sync chromite branch [master]"
-  },
-  {
-    "cmd": [
       "python",
       "-u",
       "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
       "[SLAVE_BUILD]/chromite/cbuildbot/config_dump.json",
       "/path/to/tmp/json"
     ],
     "name": "read chromite config",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@config@{@@@",
-      "@@@STEP_LOG_LINE@config@  \"x86-generic-full\": {@@@",
-      "@@@STEP_LOG_LINE@config@    \"_template\": \"full\", @@@",
-      "@@@STEP_LOG_LINE@config@    \"build_type\": \"full\"@@@",
+      "@@@STEP_LOG_LINE@config@  \"auron-paladin\": {@@@",
+      "@@@STEP_LOG_LINE@config@    \"build_type\": \"paladin\"@@@",
       "@@@STEP_LOG_LINE@config@  }@@@",
       "@@@STEP_LOG_LINE@config@}@@@",
       "@@@STEP_LOG_END@config@@@"
     ]
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "[SLAVE_BUILD]/chromite/bin/cbuildbot",
       "--buildroot",
       "[ROOT]/cbuild/external_master",
-      "--timeout",
-      "14400",
-      "--remote-trybot",
-      "--remote-version=4",
-      "x86-generic-full"
+      "--buildbot",
+      "--branch",
+      "master",
+      "--buildnumber",
+      "12345",
+      "--buildbucket-id",
+      "1337",
+      "--repo-cache",
+      "/var/cache/chrome-infra/ccompute-setup/cros-internal",
+      "--master-build-id",
+      "24601",
+      "auron-paladin"
     ],
     "cwd": "[SLAVE_BUILD]",
-    "name": "cbuildbot [x86-generic-full]"
+    "name": "cbuildbot [auron-paladin]"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]