lib/java/build.gradle: Removed jcenter() after repeated errors

[emmenlau]

There are repeated gradle errors since the jcenter server is currently not working. The build works for me when removing jcenter from the gradle / maven repositories.

• Did not create an Apache Jira ticket for trivial change.
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• If your change does not involve any code, include [skip ci] anywhere in the commit message to free up build resources.

[emmenlau]

This fixes the majority of build errors. The remaining build errors are unrelated. Merging.