cmd/tailscaled/tailscaled.service: revert recent hardening for now

It broke Debian Stretch. We'll try again later.

Updates #1245

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscaled/tailscaled.service

@@ -20,24 +20,5 @@ CacheDirectory=tailscale
 CacheDirectoryMode=0750
 Type=notify
 
-DeviceAllow=/dev/net/tun
-DeviceAllow=/dev/null
-DeviceAllow=/dev/random
-DeviceAllow=/dev/urandom
-DevicePolicy=strict
-LockPersonality=true
-MemoryDenyWriteExecute=true
-PrivateTmp=true
-ProtectClock=true
-ProtectControlGroups=true
-ProtectHome=true
-ProtectKernelTunables=true
-ProtectSystem=strict
-ReadWritePaths=/etc/
-ReadWritePaths=/run/
-ReadWritePaths=/var/run/
-RestrictSUIDSGID=true
-SystemCallArchitectures=native
-
 [Install]
 WantedBy=multi-user.target