tests::three_logserver_append_after_seal_concurrent is flaky

[tillrohrmann]

The test tests::three_logserver_append_after_seal_concurrent is flaky because the MetadataStoreProxy does encode all errors as terminal (not maintaining the property of being retryable). Therefore

restate/server/tests/common/replicated_loglet.rs

Line 167 in fb0a15e

retry_on_retryable_error(

, won't correctly retry if the current metadata cluster is unavailable.

https://github.com/restatedev/restate/actions/runs/23431522928/job/68158816809