Update Google Cloud Storage library

[tlrx]

The repository-gcs plugin is using an old version of the Google Java Client (1.23.0):

• com.google.apis:google-api-services-storage:v1-rev115-1.23
• com.google.api-client:google-api-client:1.23

This library is still supported but in maintenance mode. We should migrate the plugin to use the Cloud Client Libraries for Java instead.

This will be the opportunity to:

• revisit the security permissions required by the plugin
• address the future removal of the JSON RPC and Global HTTP Batch Endpoint (see this note on the Google Developers Blog)

[elasticmachine]

Pinging @elastic/es-distributed