Fix analyzer worker metric assignment

[languitar]

The existing formula for computing the fraction of the metrics to process for each worker subprocess could result in situations where the jobs of the last worker overlapped with the ones of the previous worker or even worse, resulted in an index exception. This commit corrects this issue.

To visualize the existing issue: With the existing calculations, having 11 metrics and 5 workers resulted in the following provisioning scheme:

1: [0, 1, 2]
2: [3, 4, 5]
3: [6, 7, 8]
4: [9, 10, 11]
5: [8, 9, 10]

Worker 4 creates an index error and worker 5 overlaps.