This was introduced by @jeswinkoshyninan in #3656

It's not clear to my why --aws-vpc-tags allows to pass a map with an arbitrary number of items if we only ever pass a single key-value pair (the one with the key specified in --aws-vpc-tag-key) as the tag filter for finding a VPC.

Shouldn't it rather just convert the map from --aws-vpc-tags into a list of tag filters, one for each item? This would remove the need for --aws-vpc-tag-key altogether.

Ref: #3656 (comment)