[v7.0/forgejo] fix: load settings for valid user and email check

- The doctor commands to check the validity of existing usernames and
email addresses depend on functionality that have configurable behavior
depending on the values of the `[service]` settings, so load them when
running the doctor command.
- Resolves #6664
- No unit test due to the architecture of doctor commands.

(cherry picked from commit 46e60ce966)

modules/setting/service.go

@@ -133,6 +133,11 @@ func CompileEmailGlobList(sec ConfigSection, keys ...string) (globs []glob.Glob)
 	return globs
 }
 
+// LoadServiceSetting loads the service settings
+func LoadServiceSetting() {
+	loadServiceFrom(CfgProvider)
+}
+
 func loadServiceFrom(rootCfg ConfigProvider) {
 	sec := rootCfg.Section("service")
 	Service.ActiveCodeLives = sec.Key("ACTIVE_CODE_LIVE_MINUTES").MustInt(180)