fix(l2): add clippy suggestions (#951)

**Motivation**

Clippy was throwing some warnings, applying it suggestions.

**Description**

Command:
```sh
cargo clippy --all-targets --all-features --workspace -- -D warnings
```

Output to Fix:
```
warning: it looks like you're manually copying between slices
  --> cmd/ethereum_rust_l2/src/commands/test.rs:77:5
   |
77 | /     for i in 0..64 {
78 | |         buffer[i] = public_key[i + 1];
79 | |     }
   | |_____^ help: try replacing the loop by: `buffer.copy_from_slice(&public_key[1..(64 + 1)]);`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_memcpy
   = note: `#[warn(clippy::manual_memcpy)]` on by default

warning: unnecessary `if let` since only the `Ok` variant of the iterator element is used
   --> cmd/ethereum_rust_l2/src/commands/test.rs:133:21
    |
133 |                       for line in lines {
    |                       ^           ----- help: try: `lines.flatten()`
    |  _____________________|
    | |
134 | |                         if let Ok(pk) = line {
135 | |                             let thread = tokio::spawn(transfer_from(
136 | |                                 pk,
...   |
144 | |                         }
145 | |                     }
    | |_____________________^
    |
help: ...and remove the `if let` statement in the for loop
   --> cmd/ethereum_rust_l2/src/commands/test.rs:134:25
    |
134 | /                         if let Ok(pk) = line {
135 | |                             let thread = tokio::spawn(transfer_from(
136 | |                                 pk,
137 | |                                 to_address.clone(),
...   |
143 | |                             threads.push(thread);
144 | |                         }
    | |_________________________^
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_flatten
    = note: `#[warn(clippy::manual_flatten)]` on by default

warning: using `clone` on type `H160` which implements the `Copy` trait
   --> cmd/ethereum_rust_l2/src/commands/test.rs:137:33
    |
137 | ...                   to_address.clone(),
    |                       ^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `to_address`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
    = note: `#[warn(clippy::clone_on_copy)]` on by default
```

cmd/ethereum_rust_l2/src/commands/test.rs

@@ -74,9 +74,7 @@ async fn transfer_from(
 
     let mut buffer = [0u8; 64];
     let public_key = libsecp256k1::PublicKey::from_secret_key(&private_key).serialize();
-    for i in 0..64 {
-        buffer[i] = public_key[i + 1];
-    }
+    buffer.copy_from_slice(&public_key[1..]);
 
     let address = H160::from(keccak(buffer));
     let nonce = client.get_nonce(address).await.unwrap();
@@ -130,18 +128,16 @@ impl Command {
                     println!("Sending to: {to_address:#x}");
 
                     let mut threads = vec![];
-                    for line in lines {
-                        if let Ok(pk) = line {
-                            let thread = tokio::spawn(transfer_from(
-                                pk,
-                                to_address.clone(),
-                                value,
-                                iterations,
-                                verbose,
-                                cfg.clone(),
-                            ));
-                            threads.push(thread);
-                        }
+                    for pk in lines.map_while(Result::ok) {
+                        let thread = tokio::spawn(transfer_from(
+                            pk,
+                            to_address,
+                            value,
+                            iterations,
+                            verbose,
+                            cfg.clone(),
+                        ));
+                        threads.push(thread);
                     }
 
                     let mut retries = 0;