Do not run F3 tests in parallel (#705)

Repeated runs on CI
shows that there is some contention when `f3_test.go` tests are run in
parallel. See #700. Avoid F3 test flakiness by running them serially.

This fixes the symptom that is test flakiness but not the root cause.
The root cause may be within one of the test dependencies.

Fixes #623, #659, #684, #699

f3_test.go

@@ -37,13 +37,11 @@ func init() {
 var manifestSenderTimeout = 10 * time.Second
 
 func TestF3Simple(t *testing.T) {
-	t.Parallel()
 	env := newTestEnvironment(t).withNodes(2).start()
 	env.waitForInstanceNumber(5, 10*time.Second, false)
 }
 
 func TestF3WithLookback(t *testing.T) {
-	t.Parallel()
 	env := newTestEnvironment(t).withNodes(2).withManifest(func(m *manifest.Manifest) {
 		m.EC.HeadLookback = 20
 	}).start()
@@ -89,7 +87,6 @@ func TestF3WithLookback(t *testing.T) {
 }
 
 func TestF3PauseResumeCatchup(t *testing.T) {
-	t.Parallel()
 	env := newTestEnvironment(t).withNodes(3).start()
 
 	env.waitForInstanceNumber(1, 30*time.Second, true)
@@ -128,7 +125,6 @@ func TestF3PauseResumeCatchup(t *testing.T) {
 }
 
 func TestF3FailRecover(t *testing.T) {
-	t.Parallel()
 	env := newTestEnvironment(t).withNodes(2)
 
 	// Make it possible to fail a single write for node 0.
@@ -159,7 +155,6 @@ func TestF3FailRecover(t *testing.T) {
 }
 
 func TestF3DynamicManifest_WithoutChanges(t *testing.T) {
-	t.Parallel()
 	env := newTestEnvironment(t).withNodes(2).withDynamicManifest()
 
 	env.start()
@@ -172,7 +167,6 @@ func TestF3DynamicManifest_WithoutChanges(t *testing.T) {
 }
 
 func TestF3DynamicManifest_WithRebootstrap(t *testing.T) {
-	t.Parallel()
 	env := newTestEnvironment(t).withNodes(2).withDynamicManifest().start()
 
 	prev := env.nodes[0].f3.Manifest()
@@ -215,7 +209,6 @@ func TestF3DynamicManifest_WithRebootstrap(t *testing.T) {
 }
 
 func TestF3DynamicManifest_WithPauseAndRebootstrap(t *testing.T) {
-	t.Parallel()
 	env := newTestEnvironment(t).withNodes(2).withDynamicManifest().start()
 
 	env.waitForInstanceNumber(10, 30*time.Second, true)
@@ -243,7 +236,6 @@ func TestF3DynamicManifest_WithPauseAndRebootstrap(t *testing.T) {
 }
 
 func TestF3LateBootstrap(t *testing.T) {
-	t.Parallel()
 	env := newTestEnvironment(t).withNodes(2).start()
 
 	// Wait till we're "caught up".