Revert "wgengine/bench: skip flaky test"

This reverts commit d707e2f7e5.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>

wgengine/bench/bench_test.go

@@ -42,7 +42,6 @@ func BenchmarkBatchTCP(b *testing.B) {
 }
 
 func BenchmarkWireGuardTest(b *testing.B) {
-	b.Skip("flaky; see https://github.com/tailscale/corp/issues/1776")
 	run(b, func(logf logger.Logf, traf *TrafficGen) {
 		setupWGTest(b, logf, traf, Addr1, Addr2)
 	})