MM-53032: Fix module path after repo rename (#23689)

It was a good decision in hindsight to keep the public module as 0.x
because this would have been a breaking change again.

https://mattermost.atlassian.net/browse/MM-53032
```release-note
Changed the Go module path from github.com/mattermost/mattermost-server/server/v8 to github.com/mattermost/mattermost/server/v8.

For the public facing module, it's path is also changed from github.com/mattermost/mattermost-server/server/public to github.com/mattermost/mattermost/server/public
```

server/public/shared/i18n/i18n.go

@@ -15,7 +15,7 @@ import (
 	"github.com/mattermost/go-i18n/i18n"
 	"github.com/mattermost/go-i18n/i18n/bundle"
 
-	"github.com/mattermost/mattermost-server/server/public/shared/mlog"
+	"github.com/mattermost/mattermost/server/public/shared/mlog"
 )
 
 const defaultLocale = "en"

server/public/shared/mlog/global_test.go

@@ -14,7 +14,7 @@ import (
 
 	"github.com/stretchr/testify/require"
 
-	"github.com/mattermost/mattermost-server/server/public/shared/mlog"
+	"github.com/mattermost/mattermost/server/public/shared/mlog"
 )
 
 func TestLoggingBeforeInitialized(t *testing.T) {