Enforce in bootstrap that dist and install must have stage at least 1

[Kobzol]

This is a continuation of my efforts to fix staging in bootstrap after the stage0 redesign. This PR gets rid of all compiler_for usages in the dist steps 🎉 The only remaining usages are in the test steps, which are my next goal, and which will be the final boss.. both because they are quite tricky, and because most of the the rest of the steps have been already fixed.

The changes are relatively straightforward, x dist defaults to stage 2, so in that case we want to use a stage 1 build compiler for everything (except stdlib, but we usually use it even there because of uplifting).

What I didn't fix yet are the docs steps, because they are very implicit right now, and fixing them deserves its own PR.

The first commit reverts the tests that I accidentally removed in #145340 🤦‍♂️ I did it in this PR to avoid further git conflicts..

Best reviewed commit-by-commit.

r? @jieyouxu

try-job: dist-i686-linux
try-job: dist-armhf-linux
try-job: dist-x86_64-linux
try-job: dist-x86_64-msvc
try-job: dist-apple-various
try-job: dist-x86_64-apple
try-job: x86_64-msvc-2