packer: bump teamcity-agent-arm volume size to 512GB

Epic: none
Release note: none

Author: rail

build/packer/teamcity-agent-arm.json

@@ -18,7 +18,7 @@
         "ssh_timeout": "10m",
         "ami_block_device_mappings": {
             "device_name": "/dev/sda1",
-            "volume_size": "256",
+            "volume_size": "512",
             "volume_type": "gp2",
             "delete_on_termination": true
         },