[BUG] Mosviz: Colored circles appear in table viewer on region selection

[PatrickOgle]

Describe the bug Whenever a new subset is added to any of the MOSviz viewers, a colored circle is added to the header of the table viewer

To Reproduce Steps to reproduce the behavior:

1. Load data in MOSviz
2. Open hammer/screwdiver tools in any viewer (image or spectrum)
3. select region tool
4. create region
5. A colored circle, with color corresponding to the color of the region/subset appears in the table viewer header.

Expected behavior Circles should not be appearing in the table viewer header.

Screenshots Here's how it looks after adding 6 subsets to different viewers

Desktop (please complete the following information):

• OS: OSX 10-13.6
• Browser: safari
• Jupyter: jupyter core : 4.7.1 jupyter-notebook : 6.4.0 qtconsole : 5.1.0 ipython : 7.24.1 ipykernel : 5.5.5 jupyter client : 6.1.12 jupyter lab : not installed nbconvert : 6.0.7 ipywidgets : 7.6.3 nbformat : 5.1.3 traitlets : 5.0.5

Package versions (please complete the following information):

macOS-10.13.6-x86_64-i386-64bit Python 3.9.4 | packaged by conda-forge | (default, May 10 2021, 22:13:15) [Clang 11.1.0 ] Numpy 1.20.3 astropy 4.2.1 specutils 1.2 spectral-cube 0.5.0 pyyaml 5.4.1 click 8.0.1 asteval 0.9.23 idna 2.10 traitlets 5.0.5 bqplot 0.12.27 bqplot-image-gl 1.4.1 glue-core 1.0.1 glue-jupyter 0.5 glue-astronomy 0.1 echo 0.5 ipyvue 1.5.0 ipyvuetify 1.6.2 ipysplitpanes 0.2.0 ipygoldenlayout 0.4.0 voila 0.2.10 vispy 0.6.6 Jdaviz 1.0.4.dev588+g42ae894

Additional context (e.g. data files) Add any other context about the problem here.

[pllim]

I think you forgot to attach a screenshot?