MM-59875: default apps enabled false (#27756)

* MM-59875: default apps enabled false

We stopped prepackaging the apps framework and stopped supporting it in
Mattermost Cloud a year ago. As part of v10, we're formally deprecating
it, while making allowances for customers who still need to transition
by not making this a breaking change immediately. To help prevent new
adoption, let's ensure the feature flag is disabled by default.

Fixes: https://mattermost.atlassian.net/browse/MM-59875

* fix tests

server/public/model/feature_flags.go

@@ -61,7 +61,7 @@ func (f *FeatureFlags) SetDefaults() {
 	f.TestFeature = "off"
 	f.TestBoolFeature = false
 	f.EnableRemoteClusterService = false
-	f.AppsEnabled = true
+	f.AppsEnabled = false
 	f.NormalizeLdapDNs = false
 	f.CallsEnabled = true
 	f.DeprecateCloudFree = false