Use global lock instead of NewExclusivePool to allow distributed lock between multiple Gitea instances (#31813)

Replace #26486 
Fix #19620

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Co-authored-by: Jason Song <i@wolfogre.com>

modules/setting/setting.go

@@ -147,6 +147,7 @@ func loadCommonSettingsFrom(cfg ConfigProvider) error {
 	loadGitFrom(cfg)
 	loadMirrorFrom(cfg)
 	loadMarkupFrom(cfg)
+	loadGlobalLockFrom(cfg)
 	loadOtherFrom(cfg)
 	return nil
 }