[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/post_acknowledgements_test.go

@@ -12,12 +12,14 @@ import (
 )
 
 func TestPostAcknowledgementsApp(t *testing.T) {
+	mainHelper.Parallel(t)
 	t.Run("SaveAcknowledgementForPost", func(t *testing.T) { testSaveAcknowledgementForPost(t) })
 	t.Run("DeleteAcknowledgementForPost", func(t *testing.T) { testDeleteAcknowledgementForPost(t) })
 	t.Run("GetAcknowledgementsForPostList", func(t *testing.T) { testGetAcknowledgementsForPostList(t) })
 }
 
 func testSaveAcknowledgementForPost(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -60,6 +62,7 @@ func testSaveAcknowledgementForPost(t *testing.T) {
 }
 
 func testDeleteAcknowledgementForPost(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 	post, err1 := th.App.CreatePostAsUser(th.Context, &model.Post{
@@ -126,6 +129,7 @@ func testDeleteAcknowledgementForPost(t *testing.T) {
 }
 
 func testGetAcknowledgementsForPostList(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 	p1, err := th.App.CreatePostAsUser(th.Context, &model.Post{