[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/email/helper_test.go

@@ -41,10 +41,19 @@ func Setup(tb testing.TB) *TestHelper {
 	if testing.Short() {
 		tb.SkipNow()
 	}
-	dbStore := mainHelper.GetStore()
-	dbStore.DropAllTables()
-	dbStore.MarkSystemRanUnitTests()
-	mainHelper.PreloadMigrations()
+
+	var dbStore store.Store
+	if mainHelper.Options.RunParallel {
+		dbStore, _, _, _ = mainHelper.GetNewStores(tb)
+		tb.Cleanup(func() {
+			dbStore.Close()
+		})
+	} else {
+		dbStore = mainHelper.GetStore()
+		dbStore.DropAllTables()
+		dbStore.MarkSystemRanUnitTests()
+		mainHelper.PreloadMigrations()
+	}
 
 	return setupTestHelper(dbStore, tb)
 }