Fix #21986 (#22035)

* Partial revert "Updates documentation around what needs to be passed in CPI. (#21633)"

* Enforces the program_id being passed explicitly by removing it from get_instruction_keyed_accounts().

* instruction_accounts => instructions_account

programs/bpf/rust/instruction_introspection/src/lib.rs

@@ -2,7 +2,6 @@
 
 extern crate solana_program;
 use solana_program::{
-    account_info::next_account_info,
     account_info::AccountInfo,
     entrypoint,
     entrypoint::ProgramResult,
@@ -25,20 +24,19 @@ fn process_instruction(
     }
 
     let secp_instruction_index = instruction_data[0];
-    let account_info_iter = &mut accounts.iter();
-    let instruction_accounts = next_account_info(account_info_iter)?;
-    assert_eq!(*instruction_accounts.key, instructions::id());
-    let data_len = instruction_accounts.try_borrow_data()?.len();
+    let instructions_account = accounts.last().ok_or(ProgramError::NotEnoughAccountKeys)?;
+    assert_eq!(*instructions_account.key, instructions::id());
+    let data_len = instructions_account.try_borrow_data()?.len();
     if data_len < 2 {
         return Err(ProgramError::InvalidAccountData);
     }
 
     let instruction = instructions::load_instruction_at_checked(
         secp_instruction_index as usize,
-        instruction_accounts,
+        instructions_account,
     )?;
 
-    let current_instruction = instructions::load_current_index_checked(instruction_accounts)?;
+    let current_instruction = instructions::load_current_index_checked(instructions_account)?;
     let my_index = instruction_data[1] as u16;
     assert_eq!(current_instruction, my_index);
 
@@ -56,7 +54,7 @@ fn process_instruction(
                 &[instruction_data[0], instruction_data[1], 1],
                 vec![AccountMeta::new_readonly(instructions::id(), false)],
             ),
-            &[instruction_accounts.clone()],
+            accounts,
         )?;
     }