Add a --no-test option to build-toolchain

[aschwaighofer]

Builds a toolchain without running tests on macos.

[aschwaighofer]

@swift-ci Please smoke test and merge

[jrose-apple]

Is this better than just changing the default? @shahmishal, @Rostepher, @zisko

[aschwaighofer]

Changing the default will need to be synchronized with the bot setups and needs to be done by folks in charge of those. This is better than not having the option at all.

I agree with you otherwise that we could just do what we do on linux: change the default and use the --test option.

[shahmishal]

‘build-toolchain’ is not used in CI, however people in the community might be using it to build toolchain for other platform.

[aschwaighofer]

@shahmishal On linux the default is to build the toolchain in the no_test preset. Only on macOS we build the preset that tests. On linux you have to add --test if you want the preset with tests.

I can change the behavior on macOS to mirror what we do on linux if that won't break CI (as you suggest) and folks are okay with that change.