fix: std Cargo.lock moved to library dir

#14358 didn't check the correct Cargo.lock existence
Perhaps it was there so the test passed, but after a new nightly
is out it is gone.

```
    Blocking waiting for file lock on package cache
error: "/home/user/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/Cargo.lock" does not exist, unable to build with the standard library, try:
        rustup component add rust-src --toolchain nightly-aarch64-apple-darwin

note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```

src/cargo/core/compiler/standard_lib.rs

@@ -73,7 +73,7 @@ pub fn resolve_std<'gctx>(
  }
 
  let src_path = detect_sysroot_src_path(target_data)?;
- let std_ws_manifest_path = src_path.join("library").join("Cargo.toml");
+ let std_ws_manifest_path = src_path.join("Cargo.toml");
  let gctx = ws.gctx();
  // TODO: Consider doing something to enforce --locked? Or to prevent the
  // lock file from being written, such as setting ephemeral.
@@ -192,7 +192,8 @@ fn detect_sysroot_src_path(target_data: &RustcTargetData<'_>) -> CargoResult<Pat
  .join("lib")
  .join("rustlib")
  .join("src")
- .join("rust");
+ .join("rust")
+ .join("library");
  let lock = src_path.join("Cargo.lock");
  if !lock.exists() {
  let msg = format!(