Fix #21346 (#21362)

Fixes the empty transaction bug in ThisInvokeContext::push() and adds a test for it to the bank.

runtime/src/builtins.rs

@@ -17,8 +17,6 @@ fn process_instruction_with_program_logging(
     instruction_data: &[u8],
     invoke_context: &mut dyn InvokeContext,
 ) -> Result<(), InstructionError> {
-    debug_assert_eq!(first_instruction_account, 1);
-
     let logger = invoke_context.get_logger();
     let program_id = invoke_context.get_caller()?;
     stable_log::program_invoke(&logger, program_id, invoke_context.invoke_depth());