Fix Goroutine leak in v2/command/formatter

[AhmedGrati]

What I did
In this PR, I fixed the Goroutine leak in the v2/command/formatter init function. The problem that we had previously, is known as The Forgotten Sender.
To fix the issue, we should simply quit the infinite loop in the Goroutine, by sending a signal that indicates that the main thread finished its execution. It's done using defer() and the quitChan channel.
A test of the Goroutine leak was added to the unit tests to make sure that the fix is working properly.

Related issue

Fixes #10157.

[ndeloof]

AFAICT, doing so after all rainbow colors have been used once, next call will block - which is not what we expect, first color should be re-used - so the loop

[AhmedGrati]

Oh makes sense, didn't know about this constraint! I will think of a different solution.

[AhmedGrati]

Done @ndeloof.

[glours]

LGTM

[AhmedGrati]

Cannot reproduce the failed e2e tests.

go test  -race -coverprofile=coverage.out -covermode=atomic -count=1 ./pkg/e2e -run ^TestCopy$
ok      github.com/docker/compose/v2/pkg/e2e    5.467s  coverage: 39.9% of statements

go test  -race -coverprofile=coverage.out -covermode=atomic -count=1 ./pkg/e2e -run ^TestLocalComposeRun$
ok      github.com/docker/compose/v2/pkg/e2e    13.272s coverage: 40.5% of statements

The error in the pipeline is really weird.

Stderr:   unknown shorthand flag: 'f' in -f

Any help would be much appreciated.

[ndeloof]

I had to revert this PR, has this breaks compose up use of color assignment

[AhmedGrati]

@ndeloof Can you give me a scenario that helps me to reproduce the error, please?

[ndeloof]

plain good old docker compose up was broken: as defer runs after init completion, the color loop hangs and we never get logs.
cleanup should take place after pluginMain execution

[AhmedGrati]

Thanks @ndeloof, I'll fix it and open a new PR.