[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/scheduled_post_job_test.go

@@ -14,6 +14,7 @@ import (
 )
 
 func TestProcessScheduledPosts(t *testing.T) {
+	mainHelper.Parallel(t)
 	t.Run("base case - happy path", func(t *testing.T) {
 		th := Setup(t).InitBasic()
 		defer th.TearDown()
@@ -266,6 +267,7 @@ func TestProcessScheduledPosts(t *testing.T) {
 }
 
 func TestHandleFailedScheduledPosts(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -354,7 +356,7 @@ func TestHandleFailedScheduledPosts(t *testing.T) {
 		// Helper function to check notifications for a specific user
 		checkUserNotification := func(user *model.User) {
 			// Wait time for notifications to be sent (adding 5 secs because it is run in a separate goroutine)
-			var timeout = 5 * time.Second
+			timeout := 5 * time.Second
 			begin := time.Now()
 			channel, appErr := th.App.GetOrCreateDirectChannel(rctx, user.Id, systemBot.UserId)
 			assert.True(t, appErr == nil)