Linux editor can fail on start due to a stale TPS library in Engine/Binaries/Linux

For 4.8, we moved LinuxNativeDialogs, a third-party library, to a different location (and also changed its API somewhat, so the old library is binary incompatible).

However, some users apparently attempt to upgrade in place, and in more than one case we have run into issues like https://answers.unrealengine.com/questions/231689/linux-error-when-run-editor-undefined-symbol-ulinu.html because the editor first tries to load an old library which is still present at the old location.

This should be an one-line change in one of Linux setup scripts (just remove the .so at the old location).

For clarity: the library was not tracked by GitDependencies previously, so users had to build it locally (and sometimes have to still).