Drops column - ci_builds_metadata.runner_features

What does this MR do and why?

In !72378 (merged), we added runtime_runner_features which replaces runner_features. This MR removes runner_features as it is no longer required.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #343389 (closed)