ITS: cleanup lines and tracklet/clusterlines changes

[f3sch]

• comments out fit weight matrix, which is currently not used and saves a few MB in memory for the lines
• uses rof-voting for the clusterlines (only useful in deltaROF, otherwise there is only one rof)
• simplifies the dca math a bit
• adds a print() for tracklets
• cleanup lines at the end of processing

[github-actions]

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[alibuild]

Error while checking build/O2/fullCI_slc9 for d8e81e6 at 2025-07-15 07:45:

No log files found

Full log here.

[f3sch]

The error is unrelated and this CI check (failing everywhere now) was previously green, not sure why it was re-run.
@mconcas @fprino is this ok for you?

[mconcas]

The error is unrelated and this CI check (failing everywhere now) was previously green, not sure why it was re-run. @mconcas @fprino is this ok for you?

To me it seems generally ok.
I am not a fan of removing the additional computation and data members, unless we are limited by that.