sync: remove TestWaitGroupMisuse2 and TestWaitGroupMisuse3
These tests are inherently nondeterministic: They exercise a racy
code path for up to one million iterations, and require that an
error occur at least once.
TestWaitGroupMisuse2 in particular is an ongoing source of trybot
flakiness.
Fixes #38163.
Change-Id: Ibbbda2c998c915333487ad262d3df6829de01c2b
Reviewed-on: https://go-review.googlesource.com/c/go/+/340249
Trust: Damien Neil <dneil@google.com>
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>