FileFingerprintStorage performance

I believe that with JENKINS-62345, as there is only one point to create the fingerprint files on the disk, and that method is synchronized, we created the context to limit the number of fingerprint we can save on disk.

This is a big performance issue when used with Maven plugin and a set of jobs with multiple modules. It creates a queue of fingerprint objects, waiting for the lock on the FileFingerprintStorage.