Add Drain to Job Management proto

[damondouglas]

This PR closes #30155 and addresses #29669 and #30250 by:

• adding a Drain method to the Job Management proto

• regenerate stubs for the Go SDK via: go generate in sdks/go/pkg/beam/model

To validate this change, I performed the following validations for each of the three SDKS:

Java validation

Using IntelliJ ran gradle tasks:

• :model:job-management:generateProto
• :runners:check NOTE: the same tests that failed here on local machine also failed in master

Python validation

Using pyenv

pip install -e ".[gcp,test]"
pytest apache_beam/runners/portability

Go validation

cd sdks
go test ./go/pkg/beam/runners/...

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (a221f98) 38.42% compared to head (9ad3079) 38.42%.
Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #30157   +/-   ##
=======================================
  Coverage   38.42%   38.42%           
=======================================
  Files         697      697           
  Lines      102215   102215           
=======================================
  Hits        39272    39272           
  Misses      61315    61315           
  Partials     1628     1628           

Flag	Coverage Δ
go	54.17% <ø> (ø)

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[lostluck]

LGTM

[lostluck]

"truncate Unbounded Restrictions"