Regenerate dialogflow client

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Here's the log from Synthtool:

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/google-cloud-clients/google-cloud-dialogflow/synth.py.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:c6231efb525569736226b1f7af7565dbc84248efafb3692a5bb1d2d8a7975d53
Status: Image is up to date for googleapis/artman:latest
synthtool > Cloning googleapis.
synthtool > Running generator for google/cloud/dialogflow/artman_dialogflow_v2.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/java.
synthtool > Running generator for google/cloud/dialogflow/artman_dialogflow_v2beta1_java.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/java.
synthtool > Running java formatter on 128 files
synthtool > Running java formatter on 6 files
synthtool > Running java formatter on 163 files
synthtool > Running java formatter on 8 files
synthtool > Running java formatter on 207 files
synthtool > Cleaned up 0 temporary directories.
synthtool > Wrote metadata to synth.metadata.