Enable to AI plugin by default (#28770)

* Enable to AI plugin by default

* Fix tests.

server/config/diff_test.go

@@ -789,6 +789,9 @@ func TestDiff(t *testing.T) {
 						"com.mattermost.calls": {
 							Enable: true,
 						},
+						"mattermost-ai": {
+							Enable: true,
+						},
 						"playbooks": {
 							Enable: true,
 						},
@@ -821,6 +824,9 @@ func TestDiff(t *testing.T) {
 						"com.mattermost.calls": {
 							Enable: true,
 						},
+						"mattermost-ai": {
+							Enable: true,
+						},
 						"playbooks": {
 							Enable: true,
 						},
@@ -845,6 +851,9 @@ func TestDiff(t *testing.T) {
 						"com.mattermost.calls": {
 							Enable: true,
 						},
+						"mattermost-ai": {
+							Enable: true,
+						},
 						"playbooks": {
 							Enable: true,
 						},