Modify Execute Process Result Assertion

[threeal]

This issue suggests modifying the execute process result assertion as follows:

• Remove the RESULT argument from the assert_execute_process function, which is used for asserting the status code of the executed process.
• By default, make the assert_execute_process function assert whether the executed process exits successfully with status code 0.
• If the ERROR argument is specified, make the assert_execute_process function assert whether the executed process exits with a failure and a status code that is not 0.