[analyzer] Incorrect completion suggestion when the rule is already in the list

[incendial]

Hi,

When the rule is already in the configuration list, but is disabled (via : false), it's still added to the list of completion items:

It should probably not be there.

[incendial]

@DanTup fyi

[dart-github-bot]

Summary: The Dart analyzer incorrectly suggests adding a rule to the configuration list even when the rule is already present but disabled. This behavior should be corrected to prevent redundant suggestions.