Merge "Removing unused rustc-1.56.1p1" am: b73352fd57 am: c7e272e0e6 am: 0832443773 am: 34b1245348

Original change: https://android-review.googlesource.com/c/platform/prebuilts/rust/+/1959421

Change-Id: I2365704e44250fc3cd3e5d89693dc2e767d06cb8