Fix for max listeners warning in file transport

[temas]

In a noisy environment line 124, and others, can quickly run into the default max listener cap. It seems to also be uselessly spammy on the logged events, but this at least disables the warning that's not helpful in this case.

[indexzero]

I'm not sure if this actually fixes the problem. I will investigate and see if this is the right approach

[indexzero]

So basically I didn't like the setMaxListeners approach because it limited any pipe scenarios. The approach I went with is a simple mutex on the file store which wont add the drain listener if it already has one from this file transport.