runtime: remove an arbitrary timeout in TestProfBuf
The failure observed in
https://build.golang.org/log/
766ad55d098ee1979ba1ae261e0813063567743e
appears to be spurious. If it is, this change will fix it.
If it is not, and somehow the Read has deadlocked,
then this change will help to diagnose it
(by causing the test to time out and dump its running goroutines).
For #56196.
Change-Id: Ic74f018384a64e95566a5b5d8126cbd59ab5e5fa
Reviewed-on: https://go-review.googlesource.com/c/go/+/528399
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>