cmd/credentials: update test password

[mobyvb]

The required minimum length for passwords on the satellite will change from 6 to 8. This change uses "password" (8 chars) instead of "123a123" (7 chars).

[dlamarmorgan]

Does the password used in pkg/common/apikey.go also need to be updated for this?

[mobyvb]

@dlamarmorgan I thought about that, but I don't think so. We don't do validation on user-managed encryption passphrase, and it is not affected by my changes in storj/storj
However, I can update that one too for consistency if you'd like.

[mobyvb]

@dlamarmorgan I went ahead and updated the passphrase for the api key - I ended up doing that in storj/storj anyway