test: fix flaky test-http2-session-timeout

[Trott]

Increase server timeout to reduce likelihood of triggering race
conditions.

Fixes: #15326

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

test http2

[Trott]

CI: https://ci.nodejs.org/job/node-test-pull-request/10031/

[Trott]

With this change, I am able to reliably run 96 concurrent versions of the test without any failures. Prior to this, the test was reliably failing with 32 concurrent versions or even less. It was also observed failing on CI on FreeBSD.

[Trott]

(Can't run a stress test until #15300 lands.)

[mcollina]

LGTM

[mcollina]

As a reference, this was introduced in #15188.

I do not see any strategy to test this differently.

cc @apapirovski @nodejs/http2

[apapirovski]

This no longer tests the timeout condition because the test only runs 40 requests 10ms apart, so it ends way before the timeout would trigger.

I have a fix in progress with a slightly different approach. Will open a PR, if you don't mind. I don't think increasing the values is enough because it seems like the reason it's failing on FreeBSD is that the server close takes too long (successful runs on that system take less than 500ms and failing ones take almost 2s).

[mcollina]

I would prefer #15338

[jasnell]

I also prefer #15338