fix: include all events in timeline regardless of parent status

[mangesh3107]

Encountered a use-case :

• parent events were missing in timeline but being referred in other events, this led to incomplete report generation.

Changes:

• Remove filter that excluded events with parent IDs, ensuring orphaned events are preserved when parent events are missing from timeline.
• Updated existing test to support new behaviour
• Added new test for missing parent event use-case

[maciejwalkowiak]

Thanks for PR @mangesh3107!