Logs: remove already-deprecated code in grafana-data

[gabor]

in #56242 and in #56077 we deprecated things in @grafana/data. we should delete them.

afterwards, we should check all the logs-related files in grafana-data, if they also contain something deprecated, and delete those too.

[grafanabot]

@gabor please add one or more appropriate labels. Here are some tips:

• if you are making an issue, TODO, or reminder for yourself or your team, please add one label that best describes the product or feature area. Please also add the issue to your project board. 🚀

• if you are making an issue for any other reason (docs typo, you found a bug, etc), please add at least one label that best describes the product or feature that you are discussing (e.g. area/alerting, datasource/loki, type/docs, type/bug, etc). Our issue triage doc also provides additional guidance on labeling. 🚀

Thank you! ❤️