MM-41988 Updated links to legacy domain about.mm.com (#19552)

* Updated links to legacy domain about.mm.com

* Legacy link updates

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* Reverting - only need to change en.json

* about.mm.com URL updates

* mattermost.org URL updates

* forum.mm.org URL update

* Update .github/ISSUE_TEMPLATE.md

* Update .github/ISSUE_TEMPLATE.md

* Un-deleted language files

* Update README.md

* Update tests/test-config.json

* fix some test due to url updating (#19787)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
Co-authored-by: Harrison Healey <harrisonmhealey@gmail.com>
Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>

plugin/example_help_test.go

@@ -108,7 +108,7 @@ func (p *HelpPlugin) MessageHasBeenPosted(c *plugin.Context, post *model.Post) {
 
 	p.API.SendEphemeralPost(post.UserId, &model.Post{
 		ChannelId: configuration.channelID,
-		Message:   "You asked for help? Checkout https://about.mattermost.com/help/",
+		Message:   "You asked for help? Checkout https://support.mattermost.com/hc/en-us",
 		Props: map[string]interface{}{
 			"sent_by_plugin": true,
 		},