Gaussian sum filter: use value rather than ptr for ForwardTrajectory

This merge request affects 1 package:

• Tracking/TrkFitter/TrkGaussianSumFilter

Adding @amorley as watcher

added Egamma Tracking master review-pending-level-1 labels

CI Result SUCCESS (hash bfb2c985)

	Athena	AthSimulation	AthGeneration	AnalysisBase
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 22115]

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit 1cf79513

added sweep:ignore label