Improve initial cov for ACTS based track finding
Similar to what was done in ACTS Examples (e.g. https://github.com/acts-project/acts/pull/3422) we want to have an adaptive covariance for q/p
as it depends on eta
and the relative pT
resolution of the detector in first order approximation.
This should improve the efficiency of the ACTS based track finding.
The logic might later be abstracted by ACTS and therefore simplified in Athena. Since this requires an orchestrated bump of ACTS, I chose to copy it in for now.
Edited by Andreas Stefl