[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/api4/oauth_test.go

@@ -15,6 +15,7 @@ import (
 )
 
 func TestCreateOAuthApp(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()
 	client := th.Client
@@ -80,6 +81,8 @@ func TestCreateOAuthApp(t *testing.T) {
 func TestUpdateOAuthApp(t *testing.T) {
 	t.Skip("https://mattermost.atlassian.net/browse/MM-62895")
 
+	mainHelper.Parallel(t)
+
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 	client := th.Client
@@ -203,6 +206,7 @@ func TestUpdateOAuthApp(t *testing.T) {
 }
 
 func TestGetOAuthApps(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()
 	client := th.Client
@@ -273,6 +277,7 @@ func TestGetOAuthApps(t *testing.T) {
 }
 
 func TestGetOAuthApp(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()
 	client := th.Client
@@ -344,6 +349,7 @@ func TestGetOAuthApp(t *testing.T) {
 }
 
 func TestGetOAuthAppInfo(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()
 	client := th.Client
@@ -413,6 +419,7 @@ func TestGetOAuthAppInfo(t *testing.T) {
 }
 
 func TestDeleteOAuthApp(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()
 	client := th.Client
@@ -486,6 +493,7 @@ func TestDeleteOAuthApp(t *testing.T) {
 }
 
 func TestRegenerateOAuthAppSecret(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t)
 	defer th.TearDown()
 	client := th.Client
@@ -561,6 +569,7 @@ func TestRegenerateOAuthAppSecret(t *testing.T) {
 }
 
 func TestGetAuthorizedOAuthAppsForUser(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 	client := th.Client
@@ -619,6 +628,7 @@ func TestGetAuthorizedOAuthAppsForUser(t *testing.T) {
 }
 
 func TestNilAuthorizeOAuthApp(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 	client := th.Client