[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/jobs/batch_worker_test.go

@@ -17,6 +17,8 @@ import (
 // TestBatchWorkerRace tests race conditions during the start/stop
 // cases of the batch worker. Use the -race flag while testing this.
 func TestBatchWorkerRace(t *testing.T) {
+	mainHelper.Parallel(t)
+
 	th := Setup(t)
 
 	worker := jobs.MakeBatchWorker(th.Server.Jobs, th.Server.Store(), 1*time.Second, func(rctx *request.Context, job *model.Job) bool {
@@ -28,6 +30,8 @@ func TestBatchWorkerRace(t *testing.T) {
 }
 
 func TestBatchWorker(t *testing.T) {
+	mainHelper.Parallel(t)
+
 	createBatchWorker := func(t *testing.T, th *TestHelper, doBatch func(rctx *request.Context, job *model.Job) bool) (*jobs.BatchWorker, *model.Job) {
 		t.Helper()
 
@@ -58,6 +62,8 @@ func TestBatchWorker(t *testing.T) {
 	}
 
 	t.Run("stop after first batch", func(t *testing.T) {
+		mainHelper.Parallel(t)
+
 		th := Setup(t).InitBasic(t)
 
 		var worker *jobs.BatchWorker
@@ -84,6 +90,8 @@ func TestBatchWorker(t *testing.T) {
 	})
 
 	t.Run("stop after second batch", func(t *testing.T) {
+		mainHelper.Parallel(t)
+
 		th := Setup(t).InitBasic(t)
 
 		var worker *jobs.BatchWorker
@@ -110,6 +118,8 @@ func TestBatchWorker(t *testing.T) {
 	})
 
 	t.Run("done after first batch", func(t *testing.T) {
+		mainHelper.Parallel(t)
+
 		th := Setup(t).InitBasic(t)
 
 		var worker *jobs.BatchWorker
@@ -133,6 +143,8 @@ func TestBatchWorker(t *testing.T) {
 	})
 
 	t.Run("done after three batches", func(t *testing.T) {
+		mainHelper.Parallel(t)
+
 		th := Setup(t).InitBasic(t)
 
 		var worker *jobs.BatchWorker