Regenerate monitoring 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-monitoring/synth.py.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:a684d40ba9a4e15946f5f2ca6b4bd9fe301192f522e9de4fff622118775f309b
Status: Image is up to date for googleapis/artman:latest
synthtool > Cloning googleapis.
synthtool > Running generator for google/monitoring/artman_monitoring.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/java.
synthtool > Running java formatter on 48 files
synthtool > Running java formatter on 5 files
synthtool > Running java formatter on 153 files
synthtool > Cleaned up 0 temporary directories.
synthtool > Wrote metadata to synth.metadata.

[codecov]

Codecov Report

Merging #6027 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@ Coverage Diff @@## master #6027 +/- ##
============================================
+ Coverage 47.37% 47.37% +<.01% + Complexity 27125 27110 -15 
============================================
Files 2516 2516 Lines 273704 273709 +5 Branches 31348 31353 +5 ============================================
+ Hits 129655 129659 +4 - Misses 134440 134441 +1 
Partials 9609 9609

Impacted Files	Coverage Δ	Complexity Δ
.../monitoring/v3/stub/MetricServiceStubSettings.java	77.83% <100%> (+0.1%)	18 <1> (ø)	⬇️
...toring/v3/stub/AlertPolicyServiceStubSettings.java	80.74% <100%> (+0.14%)	15 <1> (ø)	⬇️
...3/stub/NotificationChannelServiceStubSettings.java	77.77% <100%> (+0.1%)	20 <1> (ø)	⬇️
...d/monitoring/v3/stub/GroupServiceStubSettings.java	76.1% <100%> (+0.15%)	16 <1> (ø)	⬇️
...toring/v3/stub/UptimeCheckServiceStubSettings.java	75% <100%> (+0.15%)	16 <1> (ø)	⬇️

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