Make num-stages counter into an internal counter.

[robertwb]

This unbreaks tests that (arguably to brittly) reject extra counters.

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ValidatesRunner compliance status (on master branch)

Lang	ULR	Dataflow	Flink	Samza	Spark	Twister2
Go	---					---
Java
Python	---					---
XLang						---

Examples testing status on various runners

Lang	ULR	Dataflow	Flink	Samza	Spark	Twister2
Go	---	---	---	---	---	---	---
Java	---		---	---	---	---	---
Python	---	---	---	---	---	---	---
XLang	---	---	---	---	---	---	---

Post-Commit SDK/Transform Integration Tests Status (on master branch)

Go	Java	Python

Pre-Commit Tests Status (on master branch)

---	Java	Python	Go	Website	Whitespace	Typescript
Non-portable
Portable	---			---	---	---

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GitHub Actions Tests Status (on master branch)

See CI.md for more information about GitHub Actions CI.

[robertwb]

Follow-up from #16101

CC: @kileys

[codecov]

Codecov Report

Merging #16638 (7d3af58) into master (1351030) will increase coverage by 37.19%.
The diff coverage is n/a.

@@ Coverage Diff @@## master #16638 +/- ##
===========================================
+ Coverage 46.43% 83.63% +37.19% 
===========================================
Files 201 452 +251 Lines 19787 62095 +42308 ===========================================
+ Hits 9189 51931 +42742 - Misses 9612 10164 +552 + Partials 986 0 -986 

Impacted Files	Coverage Δ
...eam/runners/portability/fn_api_runner/fn_runner.py	90.90% <ø> (ø)
sdks/go/pkg/beam/pardo.go
sdks/go/pkg/beam/partition.go
...pkg/beam/core/runtime/xlangx/expansionx/process.go
sdks/go/pkg/beam/core/runtime/genx/genx.go
sdks/go/pkg/beam/core/metrics/store.go
...ks/go/pkg/beam/core/runtime/harness/cache_hooks.go
sdks/go/pkg/beam/core/runtime/metricsx/urns.go
sdks/go/pkg/beam/core/runtime/graphx/serialize.go
sdks/go/pkg/beam/core/util/hooks/hooks.go
... and 644 more

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[robertwb]

Run Python PreCommit

[TheNeuralBit]

I guess internal: is a concept already defined somewhere?

[robertwb]

Yeah, there's some inconsistencies here with "user" counters requiring a name and namespace and "non-user" counters using the first component of the urn as a namespace and the rest as the name.

[robertwb]

The failing tests

apache_beam.transforms.create_test.CreateTest.test_create_uses_coder_for_pickling
apache_beam.transforms.combinefn_lifecycle_test.LocalCombineFnLifecycleTest_0.test_combine

look unrelated. Trying again.

[robertwb]

Run Python PreCommit

[robertwb]

(https://issues.apache.org/jira/browse/BEAM-13769)

[TheNeuralBit]

Run Python PreCommit

[ibzib]

I tried deflaking the Actions tests but it's unlikely to work since the rate of flakes is so high, there's no way to re-run individual actions, and the flakes can affect 8 different actions... I'm just going to merge this

[TheNeuralBit]

Thanks @ibzib, I think that the flakiness is actually resolved at HEAD, but for some reason github's /merge ref is pointing to an older commit cf79c26

[TheNeuralBit]

I suppose the merge ref is likely just created once when the PR is created and not updated.