Cloudwatch Logs: Bring back support for old Cloudwatch Logs picker

[sarahzinger]

When we added support for cross-account observability in Cloudwatch, we made a updated our Cloudwatch Logs Group picker.

Previously the log groups log picker showed a list of cloudwatch log group names for a user to query from. However, when cross-account observability is enabled in AWS, there may be multiple cloudwatch log groups sharing the same name. So we designed a new cloudwatch logs picker that would also show account ids and queries by ARN rather than log group name.

However it's come to our attention that this format of querying cloudwatch logs by ARN rather than by Log Group Name is not currently supported by AWS for gov cloud accounts.

This ticket is to represent bringing back the old picker, and keeping it behind a feature flag until we can remove it.

[fridgepoet]

As a note, here's another reason to support the old CloudWatch Logs picker #74627