Search for exact match on object store bucket name

[bsquizz]

We ran into an issue where an app team had two bucket configurations for s3 object storage, similar to this:

my-secret-temp
my-secret

The requested bucket name was my-secret, but they were provided the credentials of my-secret-temp.

I'm not aware of a need to use strings.Prefix when searching for the bucket name, so we can instead just do a simple == comparison.

[gburges]

This is good, but can potentially break every/any service that relies on partial match