os: TestRootConcurrentClose fails when runtime.AddCleanup is used

[cagedmantis]

While in the process of replacing the use of runtime.SetFinalizer with runtime.AddCleanup (#70907) in the os package, the TestRootConcurrentClose tests started failing. An investigation into the build error on go.dev/cl/638555 showed that on the gotip-wasip1-wasm_wazero builder, TestRootConcurrentClose fails because the goroutine that is spawned runs continuously and never allows the the original goroutine to continue processing.

Umbrella issue: #71134

@golang/wasm

[gabyhelp]

Related Code Changes

• os: use AddCleanup to close files
• io: use runtime.AddCleanup instead of runtime.SetFinalizer
• net: use runtime.AddCleanup instead of runtime.SetFinalizer

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[cagedmantis]

Umbrella issue: #71134

[gopherbot]

Change https://go.dev/cl/640195 mentions this issue: os: skip force the goroutine to be scheduled on WASM

[cherrymui]

I'll just note that at least on my machine with wazero, go test -short -run=TestRootConcurrentClose -count=2 -v os hangs in the second run of the test even without replacing SetFinalizer with AddCleanup. So I don't think this is a bug in AddCleanup. It is more of #71134.