Chart loading with disabled downsampling does not show a loading spinner

[mattrunyon]

Description

If you have a chart that was too big to plot initially (>30k), but small enough you can disable downsampling (<250k), when you disable downsampling the plot shows as empty with no loading indicator.

Steps to reproduce

1. Run this Python

   import datetime
   from deephaven import time_table
   from deephaven.plot import Figure
   from deephaven.plot import PlotStyle
   
   t = time_table("PT1S", datetime.datetime.now() - datetime.timedelta(seconds=100000)).update(["Y=Math.sin(ii/1000)", "Z=Math.cos(ii/1000)"])
   
   plot = Figure().plot_xy(series_name="Plot", t=t, x="Timestamp", y="Y").axes(plot_style=PlotStyle.SCATTER).show()
   

2. Click "Continue" on the plot to disable downsampling

Expected results

3. Loading spinner shows while plot loads

Actual results

3. No loading spinner while plot is loading

Versions

Engine Version: 0.35.0-SNAPSHOT Web UI Version: 0.77.0 Java Version: 17.0.10 Barrage Version: 0.6.0 Browser Name: Chrome 124 OS Name: Linux