Make support search index provider customizable in SupportDashboardActivity

This commit allows the SearchIndexableRaw data to be overriden by the
support feature provider.

Similar to work in ag/31971633 allowing SupportFeatureProvider to apply overrides on the Preference

Bug: 420354473
Flag: EXEMPT no-op new APIs for partner override
Test: manual

Change-Id: I34530bbf279f551543e64216e94d8846873bfd59