[SIEM][CASE] Reduce plugin bundle size

[cnasikas]

This PR #64665 reduces significantly the size of SIEM's bundle. Still, the import from serviceNowActionType adds ~70kb to the bundle. We should see if we can reduce the size of unnecessary imports from the actions plugin.

Related: #64589

[elasticmachine]

Pinging @elastic/siem (Team:SIEM)

[cnasikas]

Moving Cases outside of security solution reduce the size of the plugin significantly.