`approval-distribution` aggression should only trigger based on approval checking lag

[sandreim]

Currently it is triggering based on relay chain lag: best - finalized

[ordian]

We might consider removing l2 aggression level. There is no evidence it actually helps anything.

[sandreim]

I also did not find any evidence that it helps overall, but I didn't test this long enough and in harsh network environments where it is supposed to help.

[sandreim]

Going to implement this. I still consider removing it but, TBH I think it would still be useful if it triggers only when network issues occur.