Currently when the default test virtual cluster is enabled, depending on test args, the test will also probabilistically select a process mode, either shared or external to run the test virtual cluster as.

An env variable, COCKROACH_TEST_TENANT, already exists for overriding the probabilistic enabling of a virtual test cluster. The proposal is to add another env variable or modify the existing env var's values to dictate the process mode if required.

Epic: CRDB-31933

Jira issue: CRDB-32856