Update CircleCI to use 'central' context for Central Portal credentials

- Change context from 'Sonatype' to 'central' for both snapshot and release deployments
- This matches the CircleCI context containing CENTRAL_TOKEN_USERNAME and CENTRAL_TOKEN_PASSWORD

Author: velo

.circleci/config.yml

@@ -516,14 +516,14 @@ workflows:
           name: 'deploy snapshot'
           requires:
             - 'snapshot'
-          context: Sonatype
+          context: central
           filters:
             <<: *master-only
 
   release:
     jobs:
       - deployRelease:
           name: 'release to maven central'
-          context: Sonatype
+          context: central
           filters:
             <<: *tags-only