Add Rails 7.2-specific test environments

[fallwith]

Presumably Rails v7.2 will be available by the time #2266 is complete. Once it is, we should create a Rails v7.2 specific environment as well.

[workato-integration]

https://new-relic.atlassian.net/browse/NR-276115

[kaylareopelle]

@fallwith, is this a dupe of #2650?

[fallwith]

@kaylareopelle I say we leave this one to specifically focus on the test/environments/rails72 directory being created and allow #2650 to deal with things like reviewing the v7.2 changelog, auditing to see if there were new notifications created, etc. If #2650 ends up creating the test/environments/rails72 directory, that'll be great. But given that we still have #2266 (asking for a test/environments/rails71 directory) after adding support for v7.1, I want to make sure v7.2's directory creation happens too.