Plain POSIX files: remove commit on close (fs.rs)

Staging every write until close broke tempfile, git, and SQLite, which
expect normal files. Actors that need an atomic publish write a temporary
file and rename it; the SDK has write_atomic for that.

cli/tests/actors/toolbox/src/main.rs

@@ -107,33 +107,6 @@ fn main() {
                     Err(error) => io_error(error),
                 }
             }
-            Some("open-truncate") => {
-                let result = (|| -> io::Result<()> {
-                    let mut file = std::fs::OpenOptions::new()
-                        .write(true)
-                        .truncate(true)
-                        .open(&path)?;
-                    file.write_all(text.as_bytes())?;
-                    open.insert(path.clone(), file);
-                    Ok(())
-                })();
-                match result {
-                    Ok(()) => json!({"type": "opened"}),
-                    Err(error) => io_error(error),
-                }
-            }
-            Some("append") => {
-                let result = (|| -> io::Result<()> {
-                    let mut file = std::fs::OpenOptions::new().append(true).open(&path)?;
-                    file.write_all(text.as_bytes())?;
-                    open.insert(path.clone(), file);
-                    Ok(())
-                })();
-                match result {
-                    Ok(()) => json!({"type": "opened"}),
-                    Err(error) => io_error(error),
-                }
-            }
             Some("close") => json!({"type": "closed", "closed": open.remove(&path).is_some()}),
             Some("arm-shutdown") => {
                 emit_shutdown = true;