Revert "[mlir] Mark `isa/dyn_cast/cast/...` member functions deprecated. (#89998)" (#90250)

This reverts commit 950b7ce0b88318f9099e9a7c9817d224ebdc6337.

This change is causing build failures on a bot
https://lab.llvm.org/buildbot/#/builders/216/builds/38157

GitOrigin-RevId: 7aedd7dc754c74a49fe84ed2640e269c25414087
1 file changed