repair_plots: make generate_plots work

Currently, the update to RLlib has moved the storage location of exploitability in the results directory. This means the exploitability results/dataframes are always empty. Furthermore, a little refactoring was done, notably for the training_iteration_metric_plot.

requested review from @siva-sri-prasanna.maddila

assigned to @siva-sri-prasanna.maddila

approved this merge request

mentioned in commit 04e78565

merged