fix: remove print maven repo username (#308)

* fix: update release pipeline to use maven token instead of user:password

* fix:revert maven-source-plugin to 3.2.1

* fix: print username for maven repo publish and revert
maven-source-plugin to 3.2.1

* fix: remove print maven repo username

---------

Co-authored-by: HKWinterhalter <HansWinterhalter@gmail.com>

.kokoro/release.sh

@@ -19,7 +19,6 @@ setup_environment_secrets() {
   export SONATYPE_USERNAME=$(cat ${KOKORO_KEYSTORE_DIR}/75669_functions-framework-java-release-bot-sonatype-password | cut -f1 -d':')
   export SONATYPE_PASSWORD=$(cat ${KOKORO_KEYSTORE_DIR}/75669_functions-framework-java-release-bot-sonatype-password | cut -f2 -d':')
   export GPG_PASSPHRASE=$(cat ${KOKORO_KEYSTORE_DIR}/70247_maven-gpg-passphrase)
-  echo $SONATYPE_USERNAME
 
   # Add the key ring files to $GNUPGHOME to verify the GPG credentials.
   export GNUPGHOME=/tmp/gpg