add Rivet ART scripts

Adding ART checks for Rivet

cc @ewelina

added 21.6 Generators labels

This merge request affects 1 package:

• Generators/EvgenJobTransforms

This merge request affects 2 files:

• Generators/EvgenJobTransforms/test/test_gen_rivet_athena.sh
• Generators/EvgenJobTransforms/test/test_gen_rivet_standalone.sh

added review-pending-level-1 label

CI Result SUCCESS (hash 3c6d9478)

	AthGeneration
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
AthGeneration: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-GCC62-CC7 730]

merged

mentioned in commit 1a2dea78

added sweep:ignore label