[bug]Issue with switching between earpiece and external speaker on iOS.

[lurongshuang]

Describe the bug
#655

On iOS, there is still a problem. Switching between Bluetooth and the phone speaker fails. It is impossible to switch from the headphone to the speaker.

setSpeakerphoneOn(true);

setAudioOutputDevice(el);

I tried both methods, but they didn't work. When the headphones are connected, the sound cannot be switched to the speaker.

Platform information
iphone 12 pro 18.1.1

Flutter version: Flutter (Channel stable, 3.24.3, on macOS 15.1.1 24B91 darwin-arm64, locale
zh-Hans-CN)