travis: enable test suite on ARM64 (#20219)

* travis: Enable ARM support

* Include fixes from 20039

* Add a trace to debug the invalid lookup issue

* Try increasing the timeout to see if the arm test passes

* Investigate the resolver issue

* Increase arm64 timeout for clique test

* increase timeout in tests for arm64

* Only test the failing tests

* Review feedback: don't export epsilon

* Remove investigation tricks+include fjl's feeback

* Revert the retry ahead of using the mock resolver

* Fix rebase errors

consensus/ethash/ethash_test.go

@@ -49,7 +49,7 @@ func TestTestMode(t *testing.T) {
 		if err := ethash.VerifySeal(nil, header); err != nil {
 			t.Fatalf("unexpected verification error: %v", err)
 		}
-	case <-time.NewTimer(time.Second).C:
+	case <-time.NewTimer(2 * time.Second).C:
 		t.Error("sealing result timeout")
 	}
 }