[9.0/Serverless] Updated outdated images of Timeline (#1349)

Contributes to #1216 by
fixing 9.0/Serverless docs.

Previews:
- [Launch Timeline from investigation
guides](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/1349/solutions/security/detect-and-alert/launch-timeline-from-investigation-guides)
-
[Timeline](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/1349/solutions/security/investigate/timeline)
- [Timeline
templates](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/1349/solutions/security/investigate/timeline-templates)

Corresponding 8.0 PR: elastic/security-docs#6819

Author: nastasha-solomon