This method gets the user name based on the token:user metadata in redis,
cleans it up to be safe for a label name (lowercase, numbers and dash or underscore only),
and update the existing instance labels adding a new one called token-user
before thhis change the allow list would only support checking the 'pool' label value
we can now specify a different label name by using the format labename=value where
the equal sign '=' is considered the separator