export maps with entry point only conditions are showing the condition as part of the generated import map key (ex. d3)

[thescientist13]

What happened?

As reported in #1405 when trying to use a library like d3, there was an error being reported in the browser

Steps to reproduce

1. Install d3 as a dependency (or similar package that has similar export conditions)
2. Run greenwood develop

Repro repo - https://github.com/ProjectEvergreen/greenwood-getting-started/compare/debug-d3?expand=1

Environment

Greenwood v0.31.0

Additional Context

This is the export map for d3

"exports": {
  "umd": "./dist/d3.min.js",
  "default": "./src/index.js"
},

Looking into the generated import map, can see that its sub condition only exports are getting included in the key