test: add open-coded defer tests for too many exits path

test: add open-coded defer tests for too many exits path

Add test cases that will disable open-coded defer when there are too
many exits path, even though number of defer statements are not greater
than 8.

Updates #14939
Updates #34481

Change-Id: If5af0e107ffc30043bc2902063f8c9b131a8bca4
Reviewed-on: https://go-review.googlesource.com/c/go/+/601635
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>