[rust-launcher] Fix duplicate error messages in LauncherError

[barakeinav1]

Context

Follow-up from PR #2326 (port node launcher to Rust). Tracked in #2598.

Problem

In crates/tee-launcher/src/error.rs, DockerRunFailed (line 18) and DockerRunFailedExitStatus (line 24) have identical #[error()] messages:

#[error("docker run failed for validated hash")]
DockerRunFailed { ... },

#[error("docker run failed for validated hash")]
DockerRunFailedExitStatus { ... },

This makes it impossible to distinguish them in logs.

Action

Give DockerRunFailedExitStatus a distinct message, e.g.:

#[error("docker run exited with non-zero status for validated hash")]