Add explicit call to EventContext constructor

which will be needed in a future version of Gaudi (see gaudi/Gaudi!1446 (merged))

added lhcb-gaudi-head label

• [2023-04-25 00:07] Validation started with lhcb-gaudi-head#3542
• [2023-04-26 00:07] Validation started with lhcb-gaudi-head#3543
• [2023-04-26 11:20] Validation started with lhcb-master-mr#7703

/ci-test

Started integration test build. Once done, check the results or the comparison to a reference build.

added ci-test-triggered label

merged

mentioned in commit 55c899ea