Only use fullReason for the disconnect packet

[DeltaEvo]

No description provided.

[wvffle]

LGTM though I don't quite understand why the tests changed now.

[DeltaEvo]

I wasn't expecting the tests to change when I implemented this, but the tests check the end reason to check the kick reason
Before my change the endReason was transformed into Chat and then used as client end reason and as disconnect packet reason
Now the endReason is only transformed for the disconnect packet so the client end reason is not a JSON string anymore

[rom1504]

What is this pr supposed to fix/improve ?

[DeltaEvo]

What is this pr supposed to fix/improve ?

Oh yeah forgot the most important part, explaining what I want to improve x)

Since the merge of #711 there is now a fullReason that can be used to use minecraft formated chat as the disconnection reason, the json object to format chat can become quickly big with formatting, so this make the Client end reason very difficult to read

fullReason also discard the first reason argument of the end function, so instead of using a minecraft formated chat json as client end reason I thought using the first string reason parameter permit us to have a more readable reason since the end reason is mostly used for debugging

PS: I will edit my commit later to specify what this change improve