[Security Solution][Notes] - remove old note system

[PhilippeOberti]

Description

We introduced in 8.15 a new system to save notes to documents and timelines. We GAed that system in 8.16.

We need to remove the old code entirely.

Acceptance criteria

• no code using the old timeline note should remain
  • delete the slice of Redux state
  • remove the timeline Notes tab old content

[elasticmachine]

Pinging @elastic/security-solution (Team: SecuritySolution)

[elasticmachine]

Pinging @elastic/security-threat-hunting (Team:Threat Hunting)

[elasticmachine]

Pinging @elastic/security-threat-hunting-investigations (Team:Threat Hunting:Investigations)