Replace savannah bugs by corresponding JIRA tasks

Some savannah urls are hard-coded in C++ files, either as comments or sometimes as error messages for users. Savannah being dead the corresponding JIRA task is stated.

added cleanup label

added backport run2 label

You were too quick, @cattanem, I was going to suggest the addition of the backport run2 label!

Good point. Thanks.

Any reason why this isn't being tested/merged?

added all-slots label

Not really. Let's have it built once before merging.

• [2020-09-04 00:10] Validation started with lhcb-lcg-dev3#1378
• [2020-09-04 00:11] Validation started with lhcb-sanitizers#664
• [2020-09-04 00:12] Validation started with lhcb-run3-cleanup#5
• [2020-09-04 00:14] Validation started with lhcb-test-efficiency#168
• [2020-09-04 00:15] Validation started with lhcb-lcg-dev4#1393
• [2020-09-04 00:20] Validation started with lhcb-head#2698
• [2020-09-04 00:22] Validation started with lhcb-gaudi-head-py3#461
• [2020-09-04 00:51] Validation started with lhcb-gaudi-head#2710
• [2020-09-04 11:45] Validation started with lhcb-head-2#1

merged

mentioned in commit d8af229d

picked the changes into the branch cherry-pick-d8af229d with commit b8fd59b4

mentioned in commit b8fd59b4

mentioned in merge request !690 (merged)

added Documentation label and removed all-slots backport run2 labels

mentioned in commit 1b9c5d7b