v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/boards/services/telemetry/mocks/ServerIface.go

@@ -5,12 +5,12 @@
 package mocks
 
 import (
-	httpservice "github.com/mattermost/mattermost-server/v6/server/platform/services/httpservice"
+	httpservice "github.com/mattermost/mattermost-server/server/v8/platform/services/httpservice"
 	mock "github.com/stretchr/testify/mock"
 
-	model "github.com/mattermost/mattermost-server/v6/model"
+	model "github.com/mattermost/mattermost-server/server/v8/model"
 
-	plugin "github.com/mattermost/mattermost-server/v6/plugin"
+	plugin "github.com/mattermost/mattermost-server/server/v8/plugin"
 )
 
 // ServerIface is an autogenerated mock type for the ServerIface type

server/boards/services/telemetry/telemetry.go

@@ -10,10 +10,10 @@ import (
 
 	rudder "github.com/rudderlabs/analytics-go"
 
-	"github.com/mattermost/mattermost-server/v6/server/boards/services/scheduler"
+	"github.com/mattermost/mattermost-server/server/v8/boards/services/scheduler"
 
-	"github.com/mattermost/mattermost-server/v6/server/channels/utils"
-	"github.com/mattermost/mattermost-server/v6/server/platform/shared/mlog"
+	"github.com/mattermost/mattermost-server/server/v8/channels/utils"
+	"github.com/mattermost/mattermost-server/server/v8/platform/shared/mlog"
 )
 
 const (

server/boards/services/telemetry/telemetry_test.go

@@ -16,7 +16,7 @@ import (
 
 	"github.com/stretchr/testify/require"
 
-	"github.com/mattermost/mattermost-server/v6/server/platform/shared/mlog"
+	"github.com/mattermost/mattermost-server/server/v8/platform/shared/mlog"
 )
 
 func mockServer() (chan []byte, *httptest.Server) {