[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/web_conn_test.go

@@ -4,7 +4,6 @@
 package app
 
 import (
-	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -19,8 +18,8 @@ import (
 // happen inside web_hub.go before the event is actually broadcasted, and checked
 // via ShouldSendEvent.
 func TestWebConnShouldSendEvent(t *testing.T) {
-	os.Setenv("MM_FEATUREFLAGS_WEBSOCKETEVENTSCOPE", "true")
-	defer os.Unsetenv("MM_FEATUREFLAGS_WEBSOCKETEVENTSCOPE")
+	mainHelper.Parallel(t)
+
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 	session, err := th.App.CreateSession(th.Context, &model.Session{UserId: th.BasicUser.Id, Roles: th.BasicUser.GetRawRoles(), TeamMembers: []*model.TeamMember{