Remove requirement for committer ECA check for validation
Currently, we require committers to be validated as well as authors to ensure people in the chain are properly vetted before merging. This is mainly a holdover from when we migrated from Gerrit checks to the API and was never removed, though there have been discussions in the past about it.
@wbeaton are we good to remove the committer check legally? They may not have written the code technically, but submitted it instead, and I don't know enough about the law to make the distinction.