Regenerate pubsub 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-pubsub/synth.py.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:5fd9aee1d82a00cebf425c8fa431f5457539562f5867ad9c54370f0ec9a7ccaa
Status: Image is up to date for googleapis/artman:latest
synthtool > Cloning googleapis.
synthtool > Running generator for google/pubsub/artman_pubsub.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/java.
synthtool > Replaced 'return InstantiatingGrpcChannelProvider\\.newBuilder\\(\\);' in src/main/java/com/google/cloud/pubsub/v1/stub/SubscriberStubSettings.java.
synthtool > Running java formatter on 43 files
synthtool > Running java formatter on 2 files
synthtool > Running java formatter on 87 files
synthtool > Cleaned up 0 temporary directories.
synthtool > Wrote metadata to synth.metadata.

[codecov]

Codecov Report

Merging #4487 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@ Coverage Diff @@## master #4487 +/- ##
============================================
- Coverage 49.16% 49.16% -0.01% 
Complexity 21913 21913 ============================================
Files 2078 2078 Lines 207048 207049 +1 Branches 24084 24084 ============================================
- Hits 101789 101787 -2 - Misses 97116 97119 +3 
Partials 8143 8143

Impacted Files	Coverage Δ	Complexity Δ
...e/cloud/pubsub/v1/stub/SubscriberStubSettings.java	85.21% <100%> (-0.06%)	28 <0> (ø)
...le/cloud/pubsub/v1/stub/PublisherStubSettings.java	84.06% <100%> (+0.12%)	20 <0> (ø)	⬇️
...gle/cloud/storage/testing/RemoteStorageHelper.java	55.28% <0%> (-2.44%)	8% <0%> (ø)

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[sduskis]

@jadekler, can you please review this one, given the fact that you made the artman config change?