ddl: fix a bug that MDL may progress unexpectedly or block forever (#46921)#47068

Merged

ti-chi-bot[bot] merged 1 commit intopingcap:release-6.5from ti-chi-bot:cherry-pick-46921-to-release-6.5

Nov 27, 2023

+55-26

Commits on Nov 23, 2023

ddl: cherrypick some PRs to fix MDL bug (pingcap#47079 )
wjhuang2016
committed