MM-18818 Prompt admins to set the Support Email (#17296)

* MM-18818 Set default support to empty and handled the same in email templates

* #MM-18818 Admin advisor now warns for inconfigured support email address

* Updated text

* #MM-18818 gofmt'ed files

* #MM-18818 updated text and removed unused i18n strings:

* #MM-18818 updated i18n string ordering

* #MM-18818 Added test for support email advisory

* MM-18818 gofmt'd the file

* MM-18818 separated contextual notifications from configuration notifications in Admin Advisor

* #MM-18818 prevented support email with whitepsaces from being detected as filled

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/config.go

@@ -134,7 +134,7 @@ const (
 	SUPPORT_SETTINGS_DEFAULT_ABOUT_LINK            = "https://about.mattermost.com/default-about/"
 	SUPPORT_SETTINGS_DEFAULT_HELP_LINK             = "https://about.mattermost.com/default-help/"
 	SUPPORT_SETTINGS_DEFAULT_REPORT_A_PROBLEM_LINK = "https://about.mattermost.com/default-report-a-problem/"
-	SUPPORT_SETTINGS_DEFAULT_SUPPORT_EMAIL         = "feedback@mattermost.com"
+	SUPPORT_SETTINGS_DEFAULT_SUPPORT_EMAIL         = ""
 	SUPPORT_SETTINGS_DEFAULT_RE_ACCEPTANCE_PERIOD  = 365
 
 	LDAP_SETTINGS_DEFAULT_FIRST_NAME_ATTRIBUTE         = ""