[MC-170076] Non-op player in spawn protection can remove leash knot by right clicking it

After ~~MC-862~~ has been fixed non-op players can still "destroy"/remove leash knots by simply right clicking them.

Start a server
Op any player other than yourself (from the console) to activate spawn protection
```
/op Notch
```
Op yourself (from the console)
```
/op @p
```
Place a fence in the spawn protection and leash a mob to it
Switch to Survival mode
```
/gamemode survival @p
```
De-op yourself
```
/deop @p
```
Left click the leash knot
You cannot destroy it as expected
Right click the leash knot
It breaks