genie_python: install script will not pick up ipython copy errors

When reviewing #6368 I noticed an error at the end of the `genie_python_install_common` script https://github.com/ISISComputingGroup/genie_python/blob/a8b870d752a1169cb19ac4057a85facb067bf8f3/package_builder/genie_python_install_common.bat#L58 Due to the pre-expansion of variables in an `if` clause the `%errorlevel%` will never reflect an actual copy error, it would need to be changed to `!errorlevel!` and `setlocal EnableDelayedExpansion` added to the script. I haven't done this at this moment in case it causes failures in the currrent release process.

## Acceptance criteria

Issue fixed as stated and any subsequent issues evaluated