[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/post.go

@@ -26,9 +26,10 @@ import (
 	"github.com/mattermost/mattermost/server/v8/platform/services/telemetry"
 )
 
+var pendingPostIDsCacheTTL = 30 * time.Second
+
 const (
 	PendingPostIDsCacheSize = 25000
-	PendingPostIDsCacheTTL  = 30 * time.Second
 	PageDefault             = 0
 )
 
@@ -146,7 +147,7 @@ func (a *App) deduplicateCreatePost(rctx request.CTX, post *model.Post) (foundPo
 	var postID string
 	nErr := a.Srv().seenPendingPostIdsCache.Get(post.PendingPostId, &postID)
 	if nErr == cache.ErrKeyNotFound {
-		if appErr := a.Srv().seenPendingPostIdsCache.SetWithExpiry(post.PendingPostId, unknownPostId, PendingPostIDsCacheTTL); appErr != nil {
+		if appErr := a.Srv().seenPendingPostIdsCache.SetWithExpiry(post.PendingPostId, unknownPostId, pendingPostIDsCacheTTL); appErr != nil {
 			return nil, model.NewAppError("deduplicateCreatePost", "api.post.deduplicate_create_post.cache_error", nil, "", http.StatusInternalServerError).Wrap(appErr)
 		}
 		return nil, nil
@@ -205,7 +206,7 @@ func (a *App) CreatePost(c request.CTX, post *model.Post, channel *model.Channel
 			return
 		}
 
-		if appErr := a.Srv().seenPendingPostIdsCache.SetWithExpiry(post.PendingPostId, savedPost.Id, PendingPostIDsCacheTTL); appErr != nil {
+		if appErr := a.Srv().seenPendingPostIdsCache.SetWithExpiry(post.PendingPostId, savedPost.Id, pendingPostIDsCacheTTL); appErr != nil {
 			err = model.NewAppError("CreatePost", "api.post.deduplicate_create_post.cache_error", nil, "", http.StatusInternalServerError).Wrap(appErr)
 		}
 	}()
@@ -371,7 +372,7 @@ func (a *App) CreatePost(c request.CTX, post *model.Post, channel *model.Channel
 
 	// Update the mapping from pending post id to the actual post id, for any clients that
 	// might be duplicating requests.
-	if appErr := a.Srv().seenPendingPostIdsCache.SetWithExpiry(post.PendingPostId, rpost.Id, PendingPostIDsCacheTTL); appErr != nil {
+	if appErr := a.Srv().seenPendingPostIdsCache.SetWithExpiry(post.PendingPostId, rpost.Id, pendingPostIDsCacheTTL); appErr != nil {
 		return nil, model.NewAppError("CreatePost", "api.post.deduplicate_create_post.cache_error", nil, "", http.StatusInternalServerError).Wrap(appErr)
 	}
 
@@ -1383,6 +1384,7 @@ func (a *App) AddCursorIdsForPostList(originalList *model.PostList, afterPost, b
 	originalList.NextPostId = nextPostId
 	originalList.PrevPostId = prevPostId
 }
+
 func (a *App) GetPostsForChannelAroundLastUnread(c request.CTX, channelID, userID string, limitBefore, limitAfter int, skipFetchThreads bool, collapsedThreads, collapsedThreadsExtended bool) (*model.PostList, *model.AppError) {
 	var lastViewedAt int64
 	var err *model.AppError
@@ -2156,7 +2158,6 @@ func (a *App) GetPostsByIds(postIDs []string) ([]*model.Post, int64, *model.AppE
 
 func (a *App) GetEditHistoryForPost(postID string) ([]*model.Post, *model.AppError) {
 	posts, err := a.Srv().Store().Post().GetEditHistoryForPost(postID)
-
 	if err != nil {
 		var nfErr *store.ErrNotFound
 		switch {