Revert "net/dns: scope quad-100 on macOS so DoH profiles aren't shadowed (#20603)" (#20771)

This reverts commit 7e01825e51d60bb93da572ea6500fa87e9effea1.

The change was merged to main accidentally. Reverting so it can go
back through review before landing again.

updates tailscale/corp#45534

Signed-off-by: Brendan Creane <bcreane@gmail.com>