MM-63652: Transition gossip encryption functionality to GA (#33349) (#33429)

Create a new config setting, and migrate the old values to new.

https://mattermost.atlassian.net/browse/MM-63652

Skip-Enterprise-PR: true

```release-note
NONE
```

* fix i18n

also fix unit tests

```release-note
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```

* For fresh installations, default to true

```release-note
NONE
```

* gofmt files

```release-note
NONE
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* Fixing some more strings

```release-note
NONE
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* Update e2e tests

```release-note
NONE
```

server/public/model/utils_test.go

@@ -1037,7 +1037,8 @@ func checkNowhereNil(t *testing.T, name string, value any) bool {
 		// Ignoring these 2 settings.
 		// TODO: remove them completely in v8.0.
 		if name == "config.BleveSettings.BulkIndexingTimeWindowSeconds" ||
-			name == "config.ElasticsearchSettings.BulkIndexingTimeWindowSeconds" {
+			name == "config.ElasticsearchSettings.BulkIndexingTimeWindowSeconds" ||
+			name == "config.ClusterSettings.EnableExperimentalGossipEncryption" {
 			return true
 		}