We have (probably incorrect) deployment instructions that tell the developer to update ios/Flutter/AppframeworkInfo.plist to match the iOS app deployment version (see #175334 for an example of the confusion). However that plist should match the App binary -miphoneos-version-min, not the app-level deployment target.

Instead of checking MinimumOSVersion into the project via the create template, we could instead remove that key from the template, have a migration to remove it from AppframeworkInfo.plist, and instead when the plist is copied to the App.framework, dynamically add the MinimumOSVersion with plutil and the correct value.

Once it's in stable, remove the deployment instructions with a note that "after Flutter 3.x this section is no longer needed"