Reenable metadata encryption when running object server tests on CI

[bdash]

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Metadata encryption was disabled in 571b1daaf55ce69cc6849f9d1951f238441a87b6 because we have yet to automate CI to be able to allow access to the keychain when the process runs. We can't use our existing approach of security unlock <keychain name> before running the job because that keychain doesn't exist until the job runs.

[jsflax]

We now test encrypted Realms in our ObjectServer tests.

Edit: This is not the same thing. My mistake.

[tgoyne]

We still have metadata encryption disabled when running tests on CI.