Summary:
`InitializeOptionsGeneral()` was overwriting many options that were already configured by OPTIONS file, potentially with the flag default values. This PR changes that function to only overwrite options in limited scenarios, as described at the top of its definition. Block cache is still a violation.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9862
Test Plan: ran under various scenarios (multi-DB, single DB, OPTIONS file, flags) and verified options are set as expected
Reviewed By: jay-zhuang
Differential Revision: D35736960
Pulled By: ajkr
fbshipit-source-id: 75b77740af37e6f5741618f8a8f5685df2417d03
690f1edf37