Don't use `store_xxx` on optional bools
# What does this PR do?

Optional bool fields in `TrainingArguments` are given the `store_true` attribute by `HFArgumentParser` which can yield to bugs (as highlighted in #7755). This PR fixes this and to avoid breaking existing scripts, removes the optional in the `evaluate_during_training` argument.

It also fixes a few instances with the right argument called (since that argument is deprecated).

Fixes #7755