Although we are still interested in having a mechanism for this (#27632), we have realised that it's more complicated. The mechanism we merged before unfortunately has a series of problems which are having a negative effect on the development flow:

1. It gets the wrong list of files to format. It formats those touched on your previous commit, not the current one, so it's highly unpredictable which files will get formatted. This can also result in additional files being committed even if they were not staged for commit.
2. It doesn't have any handling for partially-staged files (dotnet-format breaks partial commits #29768). This can result in additional unwanted lines getting committed.
3. It only sets up the hook inside build.cmd, and not in build.sh

Issue 3 could be fixed easily, and issue 1 is probably not too bad to resolve, but issue 2 is rather tricky.

Rather than continue to produce random effects on each commit, let's disable this until we're ready to merge a solid implementation.