build presets: disable iOS host tests for now
build presets: disable iOS host tests for now

Running more tests is good, but enabling these tests made some bots run
up to 6 hours.  These tests need to be separated into bots that run in
parallel with the rest.

khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift