Fix Plot.ly exporter

[astrofrog]

This makes the plot.ly exporter functional again, and removes the option to publish to the glue account (since the maximum number of plots is easily reached)

[codecov]

Codecov Report

Merging #1886 into master will decrease coverage by 0.21%.
The diff coverage is 81.25%.

@@            Coverage Diff             @@
##           master    #1886      +/-   ##
==========================================
- Coverage    85.5%   85.29%   -0.22%     
==========================================
  Files         235      235              
  Lines       20896    20875      -21     
==========================================
- Hits        17867    17805      -62     
- Misses       3029     3070      +41

Impacted Files	Coverage Δ
glue/plugins/exporters/plotly/qt/exporter.py	80.17% <75%> (-4.16%)	⬇️
glue/core/data_factories/fits.py	88.28% <75%> (ø)	⬆️
glue/plugins/exporters/plotly/export_plotly.py	75% <87.5%> (+1.41%)	⬆️
glue/app/qt/terminal.py	63.72% <0%> (-20.59%)	⬇️
glue/utils/qt/app.py	80% <0%> (-16%)	⬇️
glue/version.py	71.42% <0%> (-14.29%)	⬇️
glue/viewers/matplotlib/qt/widget.py	77.9% <0%> (-5.82%)	⬇️
glue/conftest.py	66% <0%> (-4%)	⬇️
glue/app/qt/preferences.py	90.69% <0%> (-3.49%)	⬇️
glue/viewers/matplotlib/layer_artist.py	95% <0%> (-2.5%)	⬇️
... and 4 more

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