fix/update diagnose_data_errors

[JemmaLDaniel]

What?

This PR does the following:

1. brings diagnose_data_errors.py up-to-date with current Mava JSON logging, and
2. fixes some typos and formatting errors in docstrings and error logs.

Why?

1. Currently, checking concatenated JSON data falsely errors, citing non-identical metrics across the JSON file, but plotting can execute without error!
2. Error logs are written with unnecessary tabs that affect the printing of the log, and some print statements and docstring contain grammatical errors.

How?

1. check_metric() is modified to remove elapsed_time, which prevents the false error message.