Remove `_batch` from scheduler tell() parameter names

[btjanaka]

Description

Similar to #422, this removes _batch from parameter names in the scheduler. Even here, in a part of the API that is frequently used, I still anticipate that it will not affect users much, since most will pass in arguments positionally rather than as keywords.

TODO

• [x] Rename in both schedulers
• [x] Check tests

Questions

Status

• [x] I have read the guidelines in CONTRIBUTING.md
• [x] I have formatted my code using yapf
• [x] I have tested my code by running pytest
• [x] I have linted my code with pylint
• [x] I have added a one-line description of my change to the changelog in HISTORY.md
• [x] This PR is ready to go