perf: Removed unused ConfirmationActivity member (#1234)

## Summary

**What is the goal of this PR?**

Small follow up to #909, removing an unused member variable and some
temporary debug logging.

---

### AI Usage

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Did you use AI tools to help write this code? _**NO**_

src/activities/home/MyLibraryActivity.h

@@ -11,7 +11,6 @@
 class MyLibraryActivity final : public Activity {
  private:
   // Deletion
-  bool pendingSubActivityExit = false;
   void clearFileMetadata(const std::string& fullPath);
 
   ButtonNavigator buttonNavigator;

src/activities/util/ConfirmationActivity.cpp

@@ -28,8 +28,6 @@ void ConfirmationActivity::onEnter() {
   if (!safeHeading.empty() && !safeBody.empty()) totalHeight += spacing;
 
   startY = (renderer.getScreenHeight() - totalHeight) / 2;
-  LOG_DBG("CONF", "startY: %d", startY);
-  LOG_DBG("CONF", "Heading: %s", safeHeading.c_str());
 
   requestUpdate(true);
 }