Amend Autobuild for iOS workflow to match manual steps

[pljones]

I believe they're different. The autobuild process uses Qt 6 and some hacks to generate an unsigned ipa. Xcode itself produces a signed binary which is installed to device or uploaded to AppStore Connect. I also use Qt5 as QT6 is buggy UI wise.

Originally posted by @ann0see in #3594 (comment)