Lime jello.....................?
Not being aware of your source, I cannot suggest some metaphorical meaning. But a lime avenue is literally a roadway with lime trees on either side of it.
I think it was just what they were calling the landscaping around Versailles because M.A. was very particular about the trees she wanted planted. I'm thinking that lime just refers to the color of the trees that she had planted along the paths.
Lime trees, also called linden trees, are extremely popular throughout Europe and are planted along many streets and roadways. These can be large trees and are not to be confused with the citrus lime. The genus is Tilia. If you've been to Europe, you've seen many. For instance, Unter den Linden (Beneath the limes) is a major boulevard in Berlin. Your reference sounds like a boulevard was named in MA's honor and lined with these limes.
