tests: remove legacy regression test -> double pipe

[eljefedelrodeodeljefe]

Description of change

as described at #5373

This test was introduced in 07da49b and seems to be obsolete since
96e423a, when child_process was deprecated from c++ land.

Motivation to change this is, that it requires sed and grep on
windows, yet being the only occurences of those. I decided to
propose deletion, since it's difficult to reproduce the breaking
case in the current node implementation.

Pull Request check-list

Please make sure to review and check all of these items:

• Does make -j8 test (UNIX) or vcbuild test nosign (Windows) pass with
  this change (including linting)?
• Is the commit message formatted according to CONTRIBUTING.md?
• If this change fixes a bug (or a performance problem), is a regression
  test (or a benchmark) included?
• Is a documentation update included (if this change modifies
  existing APIs, or introduces new ones)?

Affected core subsystem(s)

child_process

[jasnell]

LGTM

[jasnell]

CI: https://ci.nodejs.org/job/node-test-pull-request/2004/

[eljefedelrodeodeljefe]

@jasnell are there action items after CI? Failures seem to be unrelated.

[eljefedelrodeodeljefe]

Should be in the same category as #5750. Afterwards running the full test-suite on windows should be much simpler.

[Trott]

LGTM.

Tiniest of nits: Strictly speaking, this isn't a deprecation. So I would recommend changing the commit message to use a verb like "remove" or "delete" instead of "deprecate".

I can't imagine how removing an obsolete test could run into trouble in CI, but as always, I'm a fan of the color green, so let's run it again. https://ci.nodejs.org/job/node-test-pull-request/2170/

[eljefedelrodeodeljefe]

@Trott reworded the commit and force pushed. CI seems green 💯

[Trott]

@eljefedelrodeodeljefe Since you are now the proud owner of a commit bit on this repo, do you want to rebase against master, run CI one last time, and merge this thing?

[jasnell]

ping @eljefedelrodeodeljefe ... still want this?

[jasnell]

Closing given the lack of forward progress on this

[gibfahn]

Seems a pity to close this when the work has all been done, the checking is finished and it's had an LGTM from @Trott , it's just a matter of rebasing and landing.

I rebased here: gibfahn/node:deprecate-pipe-double , I guess we should rerun CI, though I'm not sure what it will show (this PR just removes a test).

@eljefedelrodeodeljefe care to rebase? I can open a new PR with this commit if that'd be easier.