[MM-31094] Replication Lag (#16888)

* MM-31094: Adds tooling to develop and test using a MySQL instance with replication lag. Adds some lazy lookups to fallback to master if results are not found.

* MM-31094: Removes mysql-read-replica from default docker services.

* MM-31094: Switches (store..SessionStore).Get and (store.TeamStore).GetMember to using context.Context.

* MM-31094: Updates (store.UsersStore).Get to use context.

* MM-31094: Updates (store.PostStore).Get to use context.

* MM-31094: Removes feature flag and config setting.

* MM-31094: Rolls back some master reads.

* MM-31094: Rolls a non-cache read.

* MM-31094: Removes feature flag from the store.

* MM-31094: Removes unused constant and struct field.

* MM-31094: Removes some old feature flag references.

* MM-31094: Fixes some tests.

* MM-31094: App layers fix.

* MM-31094: Fixes mocks.

* MM-31094: Don't reparse flag.

* MM-31094: No reparse.

* MM-31094: Removed unused FeatureFlags field.

* MM-31094: Removes unnecessary feature flags variable declarations.

* MM-31094: Fixes copy-paste error.

* MM-31094: Fixes logical error.

* MM-30194: Removes test method from store.

* Revert "MM-30194: Removes test method from store."

This reverts commit d5a6e8529bd5f4d993824c828e239d009b05e567.

* MM-31094: Conforming to make's strange syntax.

* MM-31094: Configures helper for read replica with option.

* MM-31094: Adds some missing ctx's.

* MM-31094: WIP

* MM-31094: Updates test names.

* MM-31094: WIP

* MM-31094: Removes unnecessary master reads.

* MM-31094: ID case changes out of scope.

* MM-31094: Removes unused context.

* MM-31094: Switches to a helper. Removes some var naming changes. Fixes a merge error.

* MM-31094: Removes SQLITE db driver ref.

* MM-31094: Layer generate fix.

* MM-31094: Removes unnecessary changes.

* MM-31094: Moves test method.

* MM-31094: Re-add previous fix.

* MM-31094: Removes make command for dev.

* MM-31094: Fix for login.

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/post.go

@@ -19,6 +19,7 @@ import (
 	"github.com/mattermost/mattermost-server/v5/shared/i18n"
 	"github.com/mattermost/mattermost-server/v5/shared/mlog"
 	"github.com/mattermost/mattermost-server/v5/store"
+	"github.com/mattermost/mattermost-server/v5/store/sqlstore"
 )
 
 const (
@@ -186,7 +187,7 @@ func (a *App) CreatePost(post *model.Post, channel *model.Channel, triggerWebhoo
 	if post.RootId != "" {
 		pchan = make(chan store.StoreResult, 1)
 		go func() {
-			r, pErr := a.Srv().Store.Post().Get(post.RootId, false, false, false)
+			r, pErr := a.Srv().Store.Post().Get(sqlstore.WithMaster(context.Background()), post.RootId, false, false, false)
 			pchan <- store.StoreResult{Data: r, NErr: pErr}
 			close(pchan)
 		}()
@@ -537,7 +538,7 @@ func (a *App) DeleteEphemeralPost(userID, postID string) {
 func (a *App) UpdatePost(post *model.Post, safeUpdate bool) (*model.Post, *model.AppError) {
 	post.SanitizeProps()
 
-	postLists, nErr := a.Srv().Store.Post().Get(post.Id, false, false, false)
+	postLists, nErr := a.Srv().Store.Post().Get(context.Background(), post.Id, false, false, false)
 	if nErr != nil {
 		var nfErr *store.ErrNotFound
 		var invErr *store.ErrInvalidInput
@@ -742,7 +743,7 @@ func (a *App) GetSinglePost(postID string) (*model.Post, *model.AppError) {
 }
 
 func (a *App) GetPostThread(postID string, skipFetchThreads, collapsedThreads, collapsedThreadsExtended bool) (*model.PostList, *model.AppError) {
-	posts, err := a.Srv().Store.Post().Get(postID, skipFetchThreads, collapsedThreads, collapsedThreadsExtended)
+	posts, err := a.Srv().Store.Post().Get(context.Background(), postID, skipFetchThreads, collapsedThreads, collapsedThreadsExtended)
 	if err != nil {
 		var nfErr *store.ErrNotFound
 		var invErr *store.ErrInvalidInput
@@ -787,7 +788,7 @@ func (a *App) GetFlaggedPostsForChannel(userID, channelID string, offset int, li
 }
 
 func (a *App) GetPermalinkPost(postID string, userID string) (*model.PostList, *model.AppError) {
-	list, nErr := a.Srv().Store.Post().Get(postID, false, false, false)
+	list, nErr := a.Srv().Store.Post().Get(context.Background(), postID, false, false, false)
 	if nErr != nil {
 		var nfErr *store.ErrNotFound
 		var invErr *store.ErrInvalidInput