Decrease the storage from 50GB to 30 GB, since we use T3Medium instance
and one executor per instance

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: I0aca5d2161d59ab225d221eb5e24726b79803225
diff --git a/packer_config.json b/packer_config.json
index 331c6b8..43c09ba 100644
--- a/packer_config.json
+++ b/packer_config.json
@@ -32,7 +32,7 @@
         {
           "device_name": "/dev/sda1",
           "volume_type": "gp2",
-          "volume_size": "50",
+          "volume_size": "30",
           "delete_on_termination": true
         }
       ]