refactor(rm): simplify preserve_root_all assignment using map_or

Replace map().unwrap_or(false) with map_or(false, ...) for more concise and idiomatic code in the rm uumain function. This change maintains the same logic while reducing redundancy.

Author: mattsu2020

src/uu/rm/src/rm.rs

@@ -256,8 +256,7 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         preserve_root: !matches.get_flag(OPT_NO_PRESERVE_ROOT),
         preserve_root_all: matches
             .get_many::<String>(OPT_PRESERVE_ROOT)
-            .map(|values| values.into_iter().any(|v| v == "all"))
-            .unwrap_or(false),
+            .map_or(false, |values| values.any(|v| v == "all")),
         recursive: matches.get_flag(OPT_RECURSIVE),
         dir: matches.get_flag(OPT_DIR),
         verbose: matches.get_flag(OPT_VERBOSE),