Fix recompiles causing Pants to be killed on M1 machines (#11580)

As of #11558, any recompile of Rust resulted in the Pants process being killed when the `native_engine.so` was not the same as before:

```
❯ MODE=debug ./pants --no-pantsd
Building native engine
    Finished dev [unoptimized + debuginfo] target(s) in 0.18s
[1]    82837 killed     MODE=debug ./pants --no-pantsd
```

The workaround is to delete `native_engine.so` beforehand, for some unknown reason. This automates that fix.

[ci skip-build-wheels]

build-support/bin/rust/bootstrap_code.sh

@@ -68,6 +68,9 @@ function bootstrap_native_code() {
     engine_version_calculated="$(calculate_current_hash)"
 
     # Create the native engine resource.
+    # NB: On Mac Silicon, for some reason, first removing the old native_engine.so is necessary to avoid the Pants
+    #  process from being killed when recompiling.
+    rm -f "${NATIVE_ENGINE_RESOURCE}"
     cp "${native_binary}" "${NATIVE_ENGINE_RESOURCE}"
 
     # Create the accompanying metadata file.