Add test to enforce that program id account info for CPI is optional (#22069) (#22103)

* Update tests to demonstrate that program id account info for CPI is optional

* Clean up comments that say that program id account info is required

(cherry picked from commit ec7536faf6)

Co-authored-by: Justin Starry <justin@solana.com>

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

@@ -54,7 +54,7 @@ fn process_instruction(
                 &[instruction_data[0], instruction_data[1], 1],
                 vec![AccountMeta::new_readonly(instructions::id(), false)],
             ),
-            accounts,
+            &[instructions_account.clone()],
         )?;
     }