Fix pixel cluster errors for FTK
The pixel cluster errors for FTK were wrongly calculated due to two reasons:
- the ErrorStrategy was set to 0 (broad errors) in the configuration, while setting 2 (errors from calibSvc) should be used
- two variables were not/wrongly initialized
This MR fixes both issues.
A discussion of these changes and the impact on the FTK pixel cluster and track parameter errors is in ATR-19602.