[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/Makefile

@@ -41,6 +41,12 @@ GOTESTSUM_FORMAT ?= testname
 GOTESTSUM_JUNITFILE ?= report.xml
 GOTESTSUM_JSONFILE ?= gotestsum.json
 
+# Go test coverage
+ENABLE_COVERAGE ?= false
+ifeq ($(ENABLE_COVERAGE),true)
+COVERAGE_FLAG = -coverprofile=cover.out -covermode=atomic
+endif
+
 # mmctl
 MMCTL_BUILD_TAGS =
 MMCTL_TESTFLAGS ?= -timeout 30m
@@ -451,7 +457,7 @@ test-server: export GOTESTSUM_FORMAT := $(GOTESTSUM_FORMAT)
 test-server: export GOTESTSUM_JUNITFILE := $(GOTESTSUM_JUNITFILE)
 test-server: export GOTESTSUM_JSONFILE := $(GOTESTSUM_JSONFILE)
 test-server: test-server-pre
-	$(GOBIN)/gotestsum --rerun-fails=3 --packages="$(TE_PACKAGES) $(EE_PACKAGES)" -- $(GOFLAGS) -timeout=90m
+	$(GOBIN)/gotestsum --rerun-fails=3 --packages="$(TE_PACKAGES) $(EE_PACKAGES)" -- $(GOFLAGS) -timeout=90m $(COVERAGE_FLAG)
 ifneq ($(IS_CI),true)
   ifneq ($(MM_NO_DOCKER),true)
     ifneq ($(TEMP_DOCKER_SERVICES),)