[release-17.0] OnlineDDL: cleanup cancelled migration artifacts; support `--retain-artifacts=<duration>` DDL strategy flag (#14029)#14037

Merged

shlomi-noach merged 2 commits intorelease-17.0from backport-14029-to-release-17.0

Sep 20, 2023

+172-3

Commits on Sep 19, 2023

Cherry-pick 0461faf with conflicts
vitess-bot[bot]
committed

Commits on Sep 20, 2023

Resolved conflict
shlomi-noach
committed