misc: replace manual From<T> for *Error with #[from]

This is a small simplification we can use since we use `thiserror`
anyway. Note that `#[from]` implies `#[source]` [0].

[0]: https://docs.rs/thiserror/2.0.12/thiserror/index.html

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com

test_infra/src/lib.rs

@@ -40,7 +40,7 @@ pub enum Error {
     #[error("Failed to parse: {0}")]
     Parsing(#[source] std::num::ParseIntError),
     #[error("ssh command failed: {0}")]
-    SshCommand(#[source] SshCommandError),
+    SshCommand(#[from] SshCommandError),
     #[error("waiting for boot failed: {0}")]
     WaitForBoot(#[source] WaitForBootError),
     #[error("reading log file failed: {0}")]
@@ -57,12 +57,6 @@ pub enum Error {
     WaitTimeout(#[source] WaitTimeoutError),
 }
 
-impl From<SshCommandError> for Error {
-    fn from(e: SshCommandError) -> Self {
-        Self::SshCommand(e)
-    }
-}
-
 pub struct GuestNetworkConfig {
     pub guest_ip: String,
     pub l2_guest_ip1: String,