[Docs migration] Cleans up investigation tools files - pt 1 (#498)

Addresses part of #559 by
doing the following:
- Removes raw migrated Serverless files that are no longer being used.
NOTE: With the exception of the Timeline page, I'm using this PR to
remove raw migrated serverless files only. After all of the my pages
have been properly aligned and version, I'll create a follow-up PR to
remove the remaining serverless images that we're no longer using.
- Adds anchors where missing and updates anchors that start with an
underscore.
- Makes minor inline adjustments to the files that were labeled as
"lift-and-shift" where appropriate.

Affected pages:
- [Investigation
tools](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate)
-
[Timeline](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/timeline)
(Some serverless images have been removed for this page only)
- [Timeline
templates](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/timeline-templates)
- [Visual event
analyzer](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/visual-event-analyzer)
- [Session
view](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/session-view)
-
[Osquery](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/osquery)
- [Manage the Osquery
integration](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/manage-integration)
- [Add Osquery Response
Actions](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/add-osquery-response-actions)
- [Run Osquery from investigation
guides](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/run-osquery-from-investigation-guides)
- [Run Osquery from
alerts](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/run-osquery-from-alerts)
- [Examine Osquery
results](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/examine-osquery-results)
- [Use placeholder fields in Osquery
queries](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/498/solutions/security/investigate/use-placeholder-fields-in-osquery-queries)

---------

Co-authored-by: natasha-moore-elastic <[email protected]>