We should be able to remove `_fullInput` entirely after dropping `transforms`

[archmoj]

Again, you should be able to remove _fullInput entirely at this point - not just in the cases where you're accessing _fullInput.index. This isn't causing any problems, it's just cruft we should remove at some point. If you want to move on and make an issue to come back to this later then sure, but here's what I see at the current state of this PR:

 ~/plotly/plotly.js/src > drop-transforms > ag _fullInput
traces/parcoords/plot.js
60:        var preGUI = fullLayout._tracePreGUI[gd._fullData[fullIndices[i]]._fullInput.uid];
119:        //     fullLayout._tracePreGUI[gd._fullData[fullIndices[i]]._fullInput.uid],

traces/table/data_preparation_helper.js
41:    var columnOrder = trace._fullInput.columnorder;

components/legend/handle_click.js
47:        fullTrace = fullTrace._fullInput;
89:        var fullInput = fullTrace._fullInput || fullTrace;
108:    var fullInput = fullTrace._fullInput;

components/legend/draw.js
113:                _fullInput: shape,
559:                var fullInput = legendItem.trace._fullInput || {};

components/selections/select.js
946:        var fullInputTrace = searchTraces[i].cd[0].trace._fullInput;
958:            trace._input.selectedpoints = trace._fullInput.selectedpoints = [];
959:            if(trace._fullInput !== trace) trace.selectedpoints = [];
970:                if(trace._fullInput !== trace) {
975:                if(trace._fullInput !== trace) {
985:            if(trace._fullInput !== trace) {
986:                delete trace._fullInput.selectedpoints;

plot_api/template_api.js
345:            if(!fullTrace._fullInput._template) {

plot_api/plot_api.js
1445:            var preGUI = fullLayout._tracePreGUI[getFullTrace(tracei)._fullInput.uid];
1517:            var preGUI = fullLayout._tracePreGUI[contFull._fullInput.uid];
2400:        if(fullData[i]._fullInput.uid === uid) return i;
2521:                fullInput = fullTrace._fullInput;
2784:            trace = newFullData[i]._fullInput;
2788:            getDiffFlags(oldFullData[i]._fullInput, trace, [], diffOpts);

plots/cartesian/type_defaults.js
121:    var isCandlestick = traceIs(trace._fullInput || {}, 'candlestick');

plots/plots.js
502:        uid = newFullData[i]._fullInput.uid;
554:        var thisFullInput = oldFullData[i]._fullInput;
1091:        fullTrace._fullInput = fullTrace;

Originally posted by @alexcjohnson in #7240 (comment)