Unify branches 8.5 and master #3914
Description
The release-8.5 branch depends on the PD release-8.5 and TiDB release-8.5 branches.
Similarly, the master branch depends on the PD master and TiDB master branches.
Due to dependency conflicts, the release-8.5 branch cannot be merged with the master branch directly. To resolve this, we should implement build tags to enable merging these two branches into a single branch.