`read_only` parameter is not compatible with `ephemeral_resync_on_open`

[jecaro]

Expected behavior

One use case of an ephemeral clone is to have a read-only replica. When giving true as the parameter read_only to the call DBCloud::Open, I expect the ephemeral clone to behave how it is supposed to and resync when it is reopened (as described in this comment).

Actual behavior

With this configuration, when we close and reopen a read_only replica with the parameter ephemeral_resync_on_open, it is not synched with the data in the cloud. But it is opened in the same state as when it was first closed.

Steps to reproduce the behavior

• run a read/write instance with a dest bucket some_bucket and put data in it, making sure it makes it to the S3 bucket
• run an instance with the source bucket sets to some_bucket, no dest bucket, ephemeral_resync_on_open sets to true and pass true as a read_only parameter of the function DBCloud::Open
• the first time, the data is synced
• add some data using the first instance and make sure it ends up in the S3 bucket
• close and reopen the read-only replica and see that the data is not synched. The newly added data is not available from the read replica.
• it works as expected when passing read_only = false to DBCloud::Open or when deleting the local directory