Static Legend: existing cells should not turn on static legend

[TCL735]

When Static Legend goes to production as a new feature, existing cells should not have a static legend turned on automatically as this is very jarring for users. And requiring users to turn off static legends for existing cells is too burdensome.

After this is merged, the following steps will confirm in Tools:

• turn off the feature flag staticLegend in ConfigCat
• create and save some cells (they won't have any static legends as it will be impossible with the feature flag off)
• turn on the feature flag staticLegend in ConfigCat (just for Tools)
• visually inspect the cells previously created to ensure they do not have a static legend (since none were created) automatically