DisaggOplogApplierImplTest and DisaggOplogTruncateMarkersTest installed DisaggregatedPersistenceProvider after the storage engine was created, resulting in them creating tables with type=file because that setting from the provider happens to be read at engine creation time. This had a few problems: it left WiredTigerKVEngine with a dangingly reference to a deleted persistence provider, it relied on specific implementation details of when WiredTigerKVEngine happened to use the provider, and unintentionally tested a very strange combination of settings.

Extract the setup needed to create layered tables in unit tests from disagg_wiredtiger_test.cpp to a shared fixture used by that, the two aforementioned suites, and some of the pali tests which had similar duplicated setup. The oplog truncation tests are now split into separate suites which operate in in-memory when possible and with the full disagg setup for tests which want to operate on layered tables.