Use remote_user to execute on_create_command and update_content_command (#54020)

KyleBarton created 

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Closes #53995

Release Notes:

- Improved dev container remote script execution to more closely align
with the reference implementation

Change summary

crates/dev_container/src/devcontainer_manifest.rs | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

Detailed changes

crates/dev_container/src/devcontainer_manifest.rs 🔗 

@@ -1875,7 +1875,7 @@ RUN sed -i -E 's/((^|\s)PATH=)([^\$]*)$/\1\${PATH:-\3}/g' /etc/profile || true
                         .run_docker_exec(
                             &devcontainer_up.container_id,
                             &remote_folder,
-                            "root",
+                            &devcontainer_up.remote_user,
                             &devcontainer_up.remote_env,
                             command,
                         )
@@ -1889,7 +1889,7 @@ RUN sed -i -E 's/((^|\s)PATH=)([^\$]*)$/\1\${PATH:-\3}/g' /etc/profile || true
                         .run_docker_exec(
                             &devcontainer_up.container_id,
                             &remote_folder,
-                            "root",
+                            &devcontainer_up.remote_user,
                             &devcontainer_up.remote_env,
                             command,
                         )
@@ -2371,8 +2371,6 @@ fn image_from_dockerfile(dockerfile_contents: String, target: &Option<String>) -
         })
 }
 
-// Container user things
-// This should come from spec - see the docs
 fn get_remote_user_from_config(
     docker_config: &DockerInspect,
     devcontainer: &DevContainerManifest,