refactor(modules): use ALabel dedup tooltip helper in simpleclock, systemd-failed-units, upower

simpleclock: migrate to updateLabelAndTooltip (label + tooltip share the
localtime arg; default tooltip falls back to the label format).
systemd-failed-units: use setLabelMarkup/setTooltipMarkup dedup setters;
label/tooltip formats are selected by different conditions so the combined
helper does not apply.
upower: use setLabelMarkup for the label; tooltip stays a custom GTK widget.
mpd already uses the dedup setters (label/tooltip use different truncated
args), so no change.

src/modules/simpleclock.cpp

@@ -18,18 +18,7 @@ auto waybar::modules::Clock::update() -> void {
   tzset();  // Update timezone information
   auto now = std::chrono::system_clock::now();
   auto localtime = fmt::localtime(std::chrono::system_clock::to_time_t(now));
-  auto text = fmt::format(fmt::runtime(format_), localtime);
-  label_.set_markup(text);
-
-  if (tooltipEnabled()) {
-    if (config_["tooltip-format"].isString()) {
-      auto tooltip_format = config_["tooltip-format"].asString();
-      auto tooltip_text = fmt::format(fmt::runtime(tooltip_format), localtime);
-      label_.set_tooltip_markup(tooltip_text);
-    } else {
-      label_.set_tooltip_markup(text);
-    }
-  }
+  updateLabelAndTooltip(format_, format_, localtime);
   // Call parent update
   ALabel::update();
 }