Enhancement for timeline templates

[angorayc]

• More unit test - [Security Solution] Template unit tests #72399
• Happy path in integration test - move to 7.10 - [Security Solution] Add tests for import / export timelines #75537
• Properly delete immutable timeline (check if it is linked to rules and handle it properly) - move to 7.10
• Internal api for on boarding template timeline
• The error message from importing timeline should be more obvious, the import modal should not be closed if it fails. - 7.10
• Update wordings for error messages.
• [ ] Update design for Template's callout message.
• Remove disableTemplate from constant.
• Fix known issue: Unexpected errors occurs when creating template timeline via import without templateTimelineId / templateTimelineVersion. - [Security Solution] Template unit tests #72399
• Decide land on Elastic template or Custom template or no filter by default
• GetAllTimeline should support retrieving all timelines at a time by calling the request twice: 1st. for the count, 2nd. for the content (instead of changing pageInfo into optional fields.) - original ticket [SIEM] Add scripts for on boarding prepackage timeline #67496 (comment) - fixed in [Security solution] Get all timeline #72690
• Wrap notes after re-import

Originally posted by @angorayc in #65448 (comment)

[elasticmachine]

Pinging @elastic/siem (Team:SIEM)