Re-apply "[AArch64] Enable "sink-and-fold" in MachineSink by default (#67432)"
This re-applies commit ace20e24, which was reverted in eff4ef25.
The issues were fixed in:
* b30765ca [AArch64] Fix an incorrect handling of debug values in
MachineSink (#68107)
* b454b04d [AArch64] Fix a compiler crash in MachineSink (#67705)