8213713: Minor issues during MetaspaceShared::initialize_runtime_shared_and_meta_spaces Summary: 1)Populate MetaspaceShared::_core_spaces_size early at mapping time; 2)Fix FileMapInfo::validate_shared_path_table to report failure properly; 3)Remove dead code in FileMapInfo::validate_shared_path_table. Reviewed-by: iklam, ccheung

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