fix(java-notebooks): ITNotebookServiceClientTest.testGetEnvironment now performs valid assertions. Add copyright to Util.java.

[burkedavison]

Resolves checkstyle failure on this project, and ensures the test is performing useful assertions.

[meltsufin]

@suztomo I thought I saw the postprocessor take care of copyright headers in some repos. Does it ring a bell?

[suztomo]

Strange. The Util.java doesn't exist in the java-notebooks repository.

https://github.com/googleapis/java-notebooks/tree/main/google-cloud-notebooks/src/test/java/com/google/cloud/notebooks/v1beta1/it

[suztomo]

It turned out the Util.java was added by Lawerence

https://github.com/googleapis/google-cloud-java/blob/main/java-notebooks/google-cloud-notebooks/src/test/java/com/google/cloud/notebooks/v1beta1/it/Util.java