Pass unsafe vault envs

[sagikazarmark]

Pass VAULT_ env vars to the test.

Note: regardless of using PassUnsafeEnv, it does seem to effect incrementality.

See the following commands:

❯ plz build --profile experimental //remote/vault:test
Build finished; total time 310ms, incrementality 100.0%. Outputs:
//remote/vault:test:
  plz-out/bin/remote/vault/test
❯ VAULT_TOKEN=asd plz build --profile experimental //remote/vault:test
Build finished; total time 19.48s, incrementality 0.0%. Outputs:
//remote/vault:test:
  plz-out/bin/remote/vault/test