[FTR][Ownership] Assign Ownership to "entity/*" ES Archives (#194436)

## Summary

Modify code owner declarations for
`x-pack/test/functional/es_archives/entity/**/*` in .github/CODEOWNERS

### For reviewers

To verify this pr, you can use the `scripts/get_owners_for_file.js`
script
E.g:
```
 node scripts/get_owners_for_file.js --file x-pack/test/functional/es_archives/entity//risks # Or any other file
```

Also, delete `x-pack/test/functional/es_archives/entity/user_risk` as
`CMD+SHIFT+F` on my MAC in VS Code, resolved zero uses.

#### Notes
All of these are a best guess effort. The more help from the dev teams,
the more accurate this will be for reporting in the future.

Contributes to: #192979

---------

Co-authored-by: kibanamachine <[email protected]>
Co-authored-by: Elastic Machine <[email protected]>
Co-authored-by: Vitalii Dmyterko <[email protected]>

.github/CODEOWNERS

@@ -1750,6 +1750,8 @@ x-pack/test/security_solution_cypress/cypress/tasks/expandable_flyout  @elastic/
 /x-pack/plugins/security_solution/common/api/detection_engine/signals_migration @elastic/security-detection-engine
 /x-pack/plugins/security_solution/common/cti @elastic/security-detection-engine
 /x-pack/plugins/security_solution/common/field_maps @elastic/security-detection-engine
+/x-pack/test/functional/es_archives/entity/risks @elastic/security-detection-engine
+/x-pack/test/functional/es_archives/entity/host_risk @elastic/security-detection-engine
 
 /x-pack/plugins/security_solution/public/sourcerer @elastic/security-threat-hunting-investigations
 /x-pack/plugins/security_solution/public/detection_engine/rule_creation @elastic/security-detection-engine