chore: Updated resource size for docker-php

Author: pchinthapenta

test/manual/definitions/apm/php-agent/docker-php-linux2.json

@@ -10,7 +10,7 @@
       "id": "doc-php-l2",
       "provider": "aws",
       "type": "ec2",
-      "size": "t3.medium",
+      "size": "t3.small",
       "ami_name": "amzn2-ami-hvm-2.0.????????.?-x86_64-gp2",
       "user_name": "ec2-user"
     }