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: sha256:38a27ba6245f96c3e86df7acb2ebcc33b4f186d9e475efe2d64303aec3d4e0ea
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.

[codecov]

Codecov Report

Merging #6128 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #6128   +/-   ##
=========================================
  Coverage     47.38%   47.38%           
  Complexity    27182    27182           
=========================================
  Files          2523     2523           
  Lines        274600   274600           
  Branches      31383    31383           
=========================================
  Hits         130124   130124           
  Misses       134863   134863           
  Partials       9613     9613

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