Remove jcenter repository

[mch2]

Description

JCenter has been turned off and should be removed as a referenced repository.

Please Remove any direct dependency on jcenter() within a repositories block in gradle files.

Related: opensearch-project/opensearch-build#1456

[peternied]

@opensearch-project/dashboards-notebooks can this be triaged and prioritized?

[joshuali925]

@peternied notebooks plugin is deprecated, we won't have new releases. see #101