Changing `at_modifier_enabled` defult value or delete this configuration

[songjiayang]

The @ modifer to stable with Prometheus v2.33, to see the PR #10121 , Whether the default value can be changed to true or delete related configuration.

I think it's time to simple cortex configurations.

[yeya24]

Agree we should enable this option by default. Same as the negative offset feature.

[alanprot]

I agree as well. Do you wanna raise a pr for it ?

[songjiayang]

very happy to