[MM-62408] Server Code Coverage with Fully Parallel Tests (#30078)

* TestPool

* Store infra

* Store tests updates

* Bump maximum concurrent postgres connections

* More infra

* channels/jobs

* channels/app

* channels/api4

* Protect i18n from concurrent access

* Replace some use of os.Setenv

* Remove debug

* Lint fixes

* Fix more linting

* Fix test

* Remove use of Setenv in drafts tests

* Fix flaky TestWebHubCloseConnOnDBFail

* Fix merge

* [MM-62408] Add CI job to generate test coverage (#30284)

* Add CI job to generate test coverage

* Remove use of Setenv in drafts tests

* Fix flaky TestWebHubCloseConnOnDBFail

* Fix more Setenv usage

* Fix more potential flakyness

* Remove parallelism from flaky test

* Remove conflicting env var

* Fix

* Disable parallelism

* Test atomic covermode

* Disable parallelism

* Enable parallelism

* Add upload coverage step

* Fix codecov.yml

* Add codecov.yml

* Remove redundant workspace field

* Add Parallel() util methods and refactor

* Fix formatting

* More formatting fixes

* Fix reporting

server/channels/app/integration_action_test.go

@@ -21,6 +21,7 @@ import (
 
 // Test for MM-13598 where an invalid integration URL was causing a crash
 func TestPostActionInvalidURL(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -71,6 +72,7 @@ func TestPostActionInvalidURL(t *testing.T) {
 }
 
 func TestPostActionEmptyResponse(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -172,6 +174,7 @@ func TestPostActionEmptyResponse(t *testing.T) {
 }
 
 func TestPostAction(t *testing.T) {
+	mainHelper.Parallel(t)
 	testCases := []struct {
 		Description string
 		Channel     func(th *TestHelper) *model.Channel
@@ -463,6 +466,7 @@ func TestPostAction(t *testing.T) {
 }
 
 func TestPostActionProps(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -547,6 +551,7 @@ func TestPostActionProps(t *testing.T) {
 }
 
 func TestSubmitInteractiveDialog(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -669,6 +674,7 @@ func TestSubmitInteractiveDialog(t *testing.T) {
 }
 
 func TestPostActionRelativeURL(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -882,6 +888,7 @@ func TestPostActionRelativeURL(t *testing.T) {
 }
 
 func TestPostActionRelativePluginURL(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -891,7 +898,7 @@ func TestPostActionRelativePluginURL(t *testing.T) {
 
 		import (
 			"net/http"
-			"encoding/json" 
+			"encoding/json"
 
 			"github.com/mattermost/mattermost/server/public/plugin"
 			"github.com/mattermost/mattermost/server/public/model"
@@ -1079,6 +1086,7 @@ func TestPostActionRelativePluginURL(t *testing.T) {
 }
 
 func TestDoPluginRequest(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()