doc,vm,test: remove _sandbox_ from vm documentation

The vm documentation uses the word _sandbox_ but has a significant disclaimer about how that should not be interpreted to connote security guarantees. Remove the term "sandbox" from documentation. As a result, some code and tests also need to change. PR-URL: #31057 Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Stephen Belanger <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]>

Author: Trott