[3.1.1 backport] Import still starts when an offline database is created

When a new database is created with the config containing "offline": true, import is still started causing xattrs to be added to documents and channel assignments to be done.

Making an offline database should not start import so import should only start when the database is brought online.

Repro steps
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1. Create a bucket with some documents
2. Create an offline database on that bucket
3. Check logs and xattrs in the bucket to see that they have been imported