Refactor: Remove program_id from process_instruction() (#20540)

* Replaces usage of program_id parameter by invoke_context.get_caller()?.

* Removes "pubkey: &Pubkey" parameter from "process_instruction()".

program-runtime/src/native_loader.rs

@@ -14,7 +14,6 @@ use solana_sdk::{
     keyed_account::keyed_account_at_index,
     native_loader,
     process_instruction::{InvokeContext, LoaderEntrypoint},
-    pubkey::Pubkey,
 };
 use std::{
     collections::HashMap,
@@ -137,12 +136,12 @@ impl NativeLoader {
 
     pub fn process_instruction(
         &self,
-        program_id: &Pubkey,
         first_instruction_account: usize,
         instruction_data: &[u8],
         invoke_context: &mut dyn InvokeContext,
     ) -> Result<(), InstructionError> {
         let (program_id, name_vec) = {
+            let program_id = invoke_context.get_caller()?;
             let keyed_accounts = invoke_context.get_keyed_accounts()?;
             let program = keyed_account_at_index(keyed_accounts, first_instruction_account)?;
             if native_loader::id() != *program_id {