Bintray is sunsetting - replace references to it and remove CD for it

[baywet]

Bintray is sunsetting in May. The alternatives would be to:

• setup artifactory cloud on Azure
• setup artifactory on a VM
• setup a feed on Azure DevOps
• setup a feed on github
• drop this platform

After internal discussions the download numbers on bintray have never been significant, having support for that platform complicates our CI/CD story.

Todo:

• update readme from service library, core and beta to remove references to bintray
• update gradle configuration for service, core and beta to remove bintray plugins
• remove environments in CD for library, core and beta
• update the webhook sample
  AB#7984

[baywet]

TODO:

• add CI/CD for android-auth + cleanup bintray +
• publish latest android auth on sonatype snapshots
• publish 0.3.0 java-auth to central