net: eliminate arbitrary timeout in TestVariousDeadlines
net: eliminate arbitrary timeout in TestVariousDeadlines

When we set a timeout, we don't actually have a guarantee one how long
the OS will take to notice it. Moreover, if the test deadlocks
completely (for example, due to a deadline never taking effect), it
would be more useful to get a full goroutine dump instead of the current
"client stuck in Dial+Copy" failure message.

For #37883
For #41863

Change-Id: I9f712ef1c620f97a5ab69baac45deb71134b99bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/371994
Trust: Bryan Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
Run-TryBot: Bryan Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

CAFxX/go,nawawi/go,cloudflare/go,golang/go,golang/go,golang/go,CAFxX/go,cloudflare/go,nawawi/go,golang/go,CAFxX/go,cloudflare/go,nawawi/go,golang/go,CAFxX/go,CAFxX/go,golang/go,nawawi/go,cloudflare/go,cloudflare/go,golang/go,nawawi/go,CAFxX/go,cloudflare/go,nawawi/go,CAFxX/go,nawawi/go,cloudflare/go,golang/go,nawawi/go,CAFxX/go,cloudflare/go