[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/import_test.go

@@ -67,6 +67,7 @@ func AssertChannelCount(t *testing.T, a *App, channelType model.ChannelType, exp
 }
 
 func TestImportImportLine(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()
 
@@ -115,6 +116,7 @@ func TestImportImportLine(t *testing.T) {
 }
 
 func TestStopOnError(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()
 
@@ -145,6 +147,7 @@ func TestStopOnError(t *testing.T) {
 }
 
 func TestImportBulkImport(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()
 
@@ -282,6 +285,7 @@ func TestImportBulkImport(t *testing.T) {
 }
 
 func TestImportProcessImportDataFileVersionLine(t *testing.T) {
+	mainHelper.Parallel(t)
 	data := imports.LineImportData{
 		Type:    "version",
 		Version: model.NewPointer(1),
@@ -451,6 +455,7 @@ func TestProcessAttachmentPaths(t *testing.T) {
 }
 
 func TestProcessAttachments(t *testing.T) {
+	mainHelper.Parallel(t)
 	c := request.TestContext(t)
 
 	genAttachments := func() *[]imports.AttachmentImportData {
@@ -633,6 +638,7 @@ func BenchmarkBulkImport(b *testing.B) {
 }
 
 func TestImportBulkImportWithAttachments(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()