Remove deprecated Figure Factory functions

[emilykl]

Partially addresses #5622

Description of change

Remove the following deprecated Figure Factory functions. All of the removed functions have alternatives in figure_factory, graph_objects, or express which can be used instead.

• create_2d_density — use plotly.express.density_heatmap instead
• create_annotated_heatmap — use plotly.express.imshow instead
• create_bullet — use plotly.graph_objects.Indicator instead
• create_candlestick — use plotly.graph_objects.Candlestick instead
• create_choropleth — use plotly.express.choropleth with custom GeoJSON instead
• create_distplot — use plotly.express functions like plotly.express.histogram instead
• create_facet_grid — use plotly.express functions with facet_row and facet_col arguments instead
• create_gantt — use plotly.express.timeline instead
• create_hexbin_mapbox — use create_hexbin_map instead
• create_ohlc — use plotly.graph_objects.Ohlc instead
• create_scatterplotmatrix — use plotly.graph_objects.Splom instead
• create_violin — use plotly.graph_objects.Violin instead

Testing strategy

Ensure test suite is passing in CI.

Can also install the package from this branch and try executing:

from plotly.figure_factory import create_2d_density  # try the name of any removed function

to ensure that an error is raised.

Guidelines

• I have reviewed the pull request guidelines and the Code of Conduct and confirm that this PR follows them.
• I have added an entry to the changelog if needed (not required for documentation PRs).

[camdecoster]

Looks good! I've got one really nitpicky suggestion.