Logs: Deprecate showContextToggle

[matyax]

In the initial implementation, there were conditions used to decide whether to show the context toggle or not for log rows. Now it seems that those conditions are no longer necessary, and we just display the option by default.

Most implementations are just returning true:

• https://github.com/grafana/grafana/blob/main/public/app/plugins/datasource/cloudwatch/datasource.ts#L155
• https://github.com/grafana/grafana/blob/main/public/app/plugins/datasource/elasticsearch/datasource.ts#L497

We should consider deprecating the option and defaulting to always display it.