Remove ML Flow dependency

[pgarrison]

We should not expect external users to run mlflow.

• Use CSV logger by default in all experiments
• Instructions should not have steps that require mlflow

[fatwir]

This has been closed with this PR (https://github.com/AllenCell/benchmarking_representations/pull/31)

[fatwir]

I have not explicitly deleted the logger in the loggers folder (I have retained this there) - let me know if I need to remove this (I have however created a csv logger and replaced all the loggers in the log files to point to this csv logger)

[pgarrison]

Re-opening because the README still references mlflow and Ritvik's work in #44 indicates that some experiments still use mlflow.