[llvm] [SystemZ] Limit latency scheduling to SUs with latency of at least 5. (PR #206459)

[Jonas Paulsson via llvm-commits]

JonPsson1 wrote:

Comment added (is it clear?)

Tests mostly auto-updated but I checked them and it is just basically reordering of the same instructions everywhere. Some superfluous LDRs (that were introduced recently) now went away again.

The schedstrategy change became implicitly tested as I had to update (and modify) the misched-prera-XXX tests.

https://github.com/llvm/llvm-project/pull/206459