"DEBUG: Computer clipboard unchanged" always printed when copying from device

- [x] I have read the [FAQ](https://github.com/Genymobile/scrcpy/blob/master/FAQ.md).
- [x] I have searched in existing [issues](https://github.com/Genymobile/scrcpy/issues).

**Environment**
- OS: Pop!_OS 22.04 LTS
- scrcpy version: 2.0
- installation method: manual build
- device model: OnePlus EB2103
- Android version: 13

**Describe the bug**
When running with `-Vdebug` and copying from the device, two messages show in the console despite copying only once:
```
[copying something new]
INFO: Device clipboard copied
DEBUG: Computer clipboard unchanged
[copying something already in computer clipboard]
DEBUG: Computer clipboard unchanged
DEBUG: Computer clipboard unchanged
```
Note that the computer clipboard is effectively changed in the first case, as I could confirm while working on #3475.

`adb logcat | grep "clipboard"` output:
```
04-14 11:28:58.831 1696 5365 D OplusClipboardController: clipboardAccessResult package: com.android.shell userCall: false
04-14 11:28:58.836 1696 4607 D OplusClipboardController: clipboardAccessResult package: com.touchtype.swiftkey userCall: false
04-14 11:28:58.852 1696 5365 D OplusClipboardController: clipboardAccessResult package: com.android.shell userCall: false
04-14 11:28:58.853 1696 1754 D OplusClipboardController: clipboardAccessResult package: com.google.android.as userCall: false
04-14 11:28:58.854 1696 7826 D OplusClipboardController: clipboardAccessResult package: com.android.systemui userCall: false
04-14 11:28:58.855 1696 4607 D OplusClipboardController: clipboardAccessResult package: com.touchtype.swiftkey userCall: false
04-14 11:28:58.858 1696 4607 D OplusClipboardController: clipboardAccessResult package: com.google.android.as userCall: false
04-14 11:28:58.879 1696 4607 D OplusClipboardController: clipboardAccessResult package: com.android.shell userCall: false
04-14 11:28:58.879 1696 1754 D OplusClipboardController: clipboardAccessResult package: com.touchtype.swiftkey userCall: false
04-14 11:28:58.880 1696 7826 D OplusClipboardController: clipboardAccessResult package: com.google.android.as userCall: false
04-14 11:28:58.937 1696 7826 D OplusClipboardController: clipboardAccessResult package: com.android.systemui userCall: false
04-14 11:28:58.963 1696 4607 D OplusClipboardController: clipboardAccessResult package: com.android.systemui userCall: false
04-14 11:29:03.698 1696 4607 W InputManager-JNI: Input channel object '[Gesture Monitor] clipboard overlay (client)' was disposed without first being removed with the input manager!
04-14 11:29:03.714 1494 1494 D Layer : reparent to null sequence=5416, seq[4], name=[Gesture Monitor] clipboard overlay#5416
04-14 11:29:03.714 1494 1494 D OplusLayer: ~Layer() sequence=5416, name=[Gesture Monitor] clipboard overlay#5416
```

Start by reproducing the clipboard copy with scrcpy 2.0 and -Vdebug, then trace the clipboard-handling entry point that emits the reported messages. Done means one copy produces accurate debug output and does not report the computer clipboard as unchanged when it was updated.

Written by the indexing model from the issue text.