Mitigate lock convoys when AtomicFactory throws

[bitfaster]

When valueFactory fails, all the threads queuing on the lock inside Initializer will call valueFactory one by one. If 100 threads are queued, and the valueFactory takes 1 second to fail, the valueFactory will be invoked 100 times, and the last thread in the list will wait for 100 seconds before getting the exception. This is a lock convoy introducing unnecessary overhead.

With this change, the 100 queued threads will all instantly fail with the same exception, and there will be 100 times fewer valueFactory calls. Subsequent calls will start from scratch.

This solution is adapted from LazyWithRetry here:
https://stackoverflow.com/a/72579523/131345

[coveralls]

coverage: 98.604% (-0.08%) from 98.681%
when pulling 24a79aa on users/alexpeck/atomicex
into 47a547e on main.