common_functions.sh does not use IMDSv2

[rstevens011]

For customers who turn off IMDSv1 the helper scripts will fail:

aws-codedeploy-samples/load-balancing/elb-v2/common_functions.sh

Line 110 in fe237a2

AWS_REGION=$(curl -s http://169.254.169.254/latest/dynamic/instance-identity/document \

Consider retrieving the IMDSv2 token before making calls like the one above.