The Go runtime uses runtime Finalizer to delete cert [[1]]. The
interestingGoroutines is able to collect stack like,
```plain
leak.go:103: Found leaked goroutined BEFORE test appears to have leaked :
sync.(*Map).LoadAndDelete(0xc00031e180, {0xe07320, 0xc00009fde0})
/usr/local/go/src/sync/map.go:272 +0x192
sync.(*Map).Delete(...)
/usr/local/go/src/sync/map.go:297
crypto/tls.(*certCache).evict(...)
/usr/local/go/src/crypto/tls/cache.go:73
crypto/tls.(*certCache).active.func1(0x0?)
/usr/local/go/src/crypto/tls/cache.go:65 +0x67
```
It's caused by GC instead of leaky goroutine. interestingGoroutines
should skip it.
Backport of #18287
[1]: 8e1fdea831/src/crypto/tls/cache.go (L63)
Signed-off-by: Wei Fu <fuweid89@gmail.com>
