[RFC][MLIR][SCF] Enable better bufferization for `TileConsumerAndFuseProducersUsingSCFForOp`

Replace iterators of the outermost loop with region arguments of the innermost
one. The changes avoid later `bufferization` passes to insert allocation within
the body of the innermost loop.

Reviewed By: mravishankar

Differential Revision: https://reviews.llvm.org/D130083