Remove certain compile-time flags

This is a tracking issue to remove the following flags from codebase:

• CONFIG_SDP (!183 (merged))
• CONFIG_NEW_INTER_MODES (!244 (merged))
• CONFIG_MRLS (!186 (merged))
• CONFIG_QBASED_QP_OFFSET (!203 (merged) )
• CONFIG_EXTQUANT (!201 (merged) )