Fix bug in phi calculation for TrigTrackSeedGenerator
The seed generator calculates the phi of the seed, It then rejects seeds which fall outside the RoI using this value of phi. A bug was introduced in 69d13708 which results in an incorrect calculation of phi. This change fixes the issue. This issue was spotted in !65003 (merged)
JIRA: ATR-28202
Edited by Benjamin Philip Kerridge