[Obs UX Management] Audit and address identification of remote cluster index patterns via single colon searches

[jasonrhodes]

More information in this issue. The following assumptions will no longer be valid:

• Presence of a ":" character in an index pattern string means that the index pattern contains a remote cluster prefix
• Splitting an index pattern string that contains a ":" on that ":" will result in the first item being the remote cluster prefix

Instead, we must be prepared for index pattern strings to present the following pattern:

{remote_cluster}:{index_name}::{failure_store_suffix}

Searching via a regex (e.g. /^([^:]+):[^:]/) would be a more future-proof way of targeting a remote cluster name while avoiding the double colon syntax. There may be other ways, depending on what you are attempting.

Concrete examples of this problem will be addressed in separate issues attached to this one as sub-issues.

[elasticmachine]

Pinging @elastic/obs-ux-management-team (Team:obs-ux-management)