add UDP listener to metron

[#74960262]

Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>
automatic promotion by GoCD workflow LoggregatorIntegrationTest/48 > IntegrationTests/1 > IntegrationTests

tests passed against https://github.com/cloudfoundry/cf-release/commit/316adad1c8513e882c8a91f6e5b7efce03871e06