These were added by commit e29a92f525 (Xcode: Make BundleTests
compatible with Xcode 11, 2019-09-01, v3.16.0-rc1~158^2). The
real problem is that the `.app` is constructed with text files
under the `.app/Contents/MacOS/` folder. Move those, and drop
the special no-signing configuration.
For `MACOSX_BUNDLE` targets we generate an `Info.plist` automatically
and add it to the sources presented to Xcode. Avoid mutating the
original target's list of sources to achieve this. Otherwise when we
generate the same target again (e.g. in a sub-project's Xcode file) it
will look different than the first time and possibly break invariants.
Fixes: #19114