Remove file locking
Overview
In !1496 (merged) we introduced file locking to solve problems where we have two Runner process running at the same time as explained in #4407 (closed). This caused a number of regressions mentioned below. At the moment we don't have a solution which will cover all the cases, and is causing some problems for users. We have discussed solution such as adding a log line if the directory is not readable and then having it a hard requirement in 13.0 but having the config directory readable only is still a valid use case, also this breaks things like NixOS as explained in #5024
For now, remove file locking, and re-introduce this in #5412 (closed) with a proper solution.