nixos/acme: Fix webroot issues

With the UMask set to 0023, the
mkdir -p command which creates the webroot
could end up unreadable if the web server
changes, as surfaced by the test suite in #114751
On top of this, the following commands
to chown the webroot + subdirectories was
mostly unnecessary. I stripped it back to
only fix the deepest part of the directory,
resolving #115976, and reintroduced a
human readable error message.

0 files changed, 0 insertions, 0 deletions