Describe the bug
from this PR's configuration #8717 Configurable data source for offloaded messages , we could set data read priority bookkeeper-first or tiered-storage-first by cli cmd or set managedLedgerDataReadPriority in broker.conf.
but seem it not work when i set managedLedgerDataReadPriority in broker.conf

To Reproduce
write a unit-test in ServiceConfigurationTest

1. set managedLedgerDataReadPriority=bookkeeper-first in configurations/pulsar_broker_test.conf
2. init serviceConfig and run test to create offloadPolicies by serviceConfig
3. check if offloadPolicies's ReadPriority equals to bookkeeper-first

Expected behavior
offloadPolicies's ReadPriority equals to bookkeeper-first & the unit test pass

Screenshots
configurations/pulsar_broker_test.conf

unit test

unit test failed

Desktop (please complete the following information):

• OS: local unit test

Additional context
Add any other context about the problem here.