Fix wrong inverse_of resulting in wrongly preloaded data
Fix wrong inverse_of resulting in wrongly preloaded data

The wrong inverse_of resulted in the following issue when preloaded
relations on spans:

    irb(main):005:0> t.spans.map(&:trace_id).uniq
    => [<UUID4:3b25610a-145c-49d6-bedf-b0e10b86b174>]

    irb(main):006:0> t.spans.includes(:traces).map(&:trace_id).uniq
    => [<UUID4:3b25610a-145c-49d6-bedf-b0e10b86b174>,
        <UUID4:7c50fe4f-4a1a-4602-90a7-e2699be56f8e>,
        <UUID4:5d5fcf3a-b4f8-4854-b137-41d14e8672c3>]

jgraichen/mnemosyne-server,jgraichen/mnemosyne-server,jgraichen/mnemosyne-server