fix failing TrkVKalVrtFitter test
see [http://atlas-computing.web.cern.ch/atlas-computing/links/distDirectory/gitwww/PRODUCTIONWebArea/ardoc_web_areamain64BC7G11AthenaOpt/ARDOC_TestLog_2023-09-27T2101/Tracking_TrkVertexFitter_TrkVKalVrtFitter___TrkVKalVrtFitterConf__TrkVKalVrtFitterTest__m.html]
Probably related to [!65922 (merged)] by @vkost