This prefers the newer types from '@elastic/elasticsearch'.

There was one instance where mock data was insufficient to satisfy the
newer analogous types; in all other cases this was just a find/replace.

We know that this mock has hits with _source values, but we cannot
convey this to typescript as null assertions are disabled within this
project. This seems like the next best solution, preferable to a
@ts-expect-error.

* refactors destructuring due to _source being properly declared as
  conditional

Changes here fall into one of two categories:

* If the test was making an assertion on a value from _source, we simply
null chain and continue to assert on a possibly undefined value.

* If the test logic depends on _source being present, we first assert that
presence, and exit the test early if absent.

 Conflicts:
	x-pack/plugins/security_solution/public/cases/components/case_view/index.tsx