perf(turbopack): Remove needless clone of sourcemap (#78972)
### What?
Use `sourcemap::SourceMap::adjust_mapping` directly instead of relying on `swc_common`.
### Why?
https://github.com/swc-project/swc/blob/6750459d9180048a39c11e14b02c9bfed251a12e/crates/swc_common/src/source_map.rs#L1385-L1388
```rust
if let Some(mut orig) = orig.cloned() {
orig.adjust_mappings(&map);
return orig;
}
```
If we pass `orig,` the original source map is cloned. I'll fix this API issue from the SWC side in the future.
x-ref, numbers: https://vercel.slack.com/archives/C03EWR7LGEN/p1746729015204369?thread_ts=1746727709.014039&cid=C03EWR7LGEN
