Refactor acloud.public.errors to acloud.errors.

Bug: 113753798
Test: atest acloud_test && run acloud create/list/delete
Change-Id: I03b4b34769d754bfebd279895b0ca44311bbecc7
diff --git a/internal/lib/android_build_client.py b/internal/lib/android_build_client.py
index 735c0e4..32a1179 100644
--- a/internal/lib/android_build_client.py
+++ b/internal/lib/android_build_client.py
@@ -21,9 +21,8 @@
 
 import apiclient
 
-from acloud import errors as root_errors
+from acloud import errors
 from acloud.internal.lib import base_cloud_client
-from acloud.public import errors
 
 logger = logging.getLogger(__name__)
 
@@ -173,7 +172,7 @@
         build = self.Execute(api)
         if build:
             return str(build.get("builds")[0].get("buildId"))
-        raise root_errors.GetBuildIDError(
+        raise errors.GetBuildIDError(
             "No available good builds for branch: %s target: %s"
             % (build_branch, build_target)
         )