[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

.github/workflows/server-ci-template.yml

@@ -264,6 +264,18 @@ jobs:
       datasource: mmuser:mostest@tcp(mysql:3306)/mattermost_test?charset=utf8mb4&multiStatements=true&maxAllowedPacket=4194304
       drivername: mysql
       logsartifact: mysql-server-test-logs
+  test-coverage:
+    name: Generate Test Coverage
+    needs: check-mattermost-vet
+    uses: ./.github/workflows/server-test-template.yml
+    secrets: inherit
+    with:
+      name: Generate Test Coverage
+      datasource: postgres://mmuser:mostest@postgres:5432/mattermost_test?sslmode=disable&connect_timeout=10
+      drivername: postgres
+      logsartifact: coverage-server-test-logs
+      fullyparallel: true
+      enablecoverage: true
   test-mmctl:
     name: Run mmctl tests
     needs: check-mattermost-vet