Drop -f flag from systemd service to allow default-less startup

With -f, the config file is mandatory and the service enters a
restart loop if it does not exist.  Without -f, the default
/etc/thinproxy.conf is silently ignored if missing, and the
proxy starts with built-in defaults.

Author: renaudallard

thinproxy.service

@@ -4,7 +4,7 @@ After=network.target
 
 [Service]
 Type=simple
-ExecStart=/usr/local/bin/thinproxy -f /etc/thinproxy.conf
+ExecStart=/usr/local/bin/thinproxy
 Restart=on-failure
 RestartSec=5
 
@@ -17,7 +17,6 @@ PrivateDevices=yes
 ProtectKernelTunables=yes
 ProtectKernelModules=yes
 ProtectControlGroups=yes
-ReadOnlyPaths=/etc/thinproxy.conf
 RestrictNamespaces=yes
 RestrictSUIDSGID=yes
 MemoryDenyWriteExecute=yes