Fix default worker capacity

[akrambek]

Fix #1456

[jfallows]

I realized that although we default workers to available processors, the calculation should actually be based on workers, not numberOfCores.

So, we actually only need osBean for getTotalMemorySize().

For workers, we would do this instead.

int workers = ENGINE_WORKERS.getAsInt(config);

Also, for clarity suggest we do the following:

int workerBufferCapacity = slotCapacity + slotCapacity + budgetBufferCapacity;
int totalBufferCapacity = workerBufferCapacity * workers;

[jfallows]

Suggested change

	long maxAllowedForMemory = (long) (percentMemory * totalMemorySize) - totalEventsBufferCapacity;
	Path directory = Paths.get(ENGINE_DIRECTORY.get(config));
	long usableDiskSpace = directory.toFile().getUsableSpace();
	long maxAllowedForBuffers = Math.min(maxAllowedForMemory, usableDiskSpace);
	long maxMemoryBufferCapacity = (long) (percentMemory * totalMemorySize) - totalEventsBufferCapacity;
	Path directory = Paths.get(ENGINE_DIRECTORY.get(config));
	long usableDiskSpace = directory.toFile().getUsableSpace()
	double percentDisk = ENGINE_DISK_PERCENTAGE.get(config);
	long maxDiskBufferCapacity = (long) (percentDisk * usableDiskSpace);
	long maxBufferCapacity = Math.min(maxMemoryBufferCapacity, maxDiskBufferCapacity);

[jfallows]

Suggested change

	int newWorkersCapacity = (int) (maxAllowedForBuffers / totalBufferCapacity);
	int newWorkersCapacity = Integer.highestOneBit((int) (maxBufferCapacity / totalBufferCapacity));

[jfallows]

With the use of Integer.highestOneBit(...) above, we can remove this, agree?