deprecate no longer required concat_alternatives

lhcb/Rec!3599 (merged) removes the last (unnecessary!) use of concat_alternatives from LHCb code -- so it is time to flag this code as deprecated, to be followed with removal at some point in the future.

added code cleanup label

assigned to @clemenci

added lhcb-gaudi-head label

changed milestone to %v37r2

• [2023-11-03 00:03] Validation started with lhcb-gaudi-head#3732
• [2023-11-03 00:07] Validation started with lhcb-run2-gaudi-head#642
• [2023-11-03 00:17] Validation started with lhcb-sim10-gaudi-head#423
• [2023-11-04 00:03] Validation started with lhcb-gaudi-head#3733
• [2023-11-04 00:11] Validation started with lhcb-run2-gaudi-head#643
• [2023-11-04 00:18] Validation started with lhcb-sim10-gaudi-head#424

approved this merge request

resolved all threads

added 1 commit

• d78bdabd - avoid warning from deprecated function

Compare with previous version

approved this merge request

merged

mentioned in commit 70db3fab