Building lighting after map data is built dirties level

There is an issue occurring where after the map built data is made building lighting on a level causes the level to become dirty. this occurs even if anything in the level has not been changed except the building process. It is unsure if this is intended behavior. This issue is not a regression.

Versions Tested: This issue occurs in all versions tested
4.16.3 - CL: 3561208
4.17.2 - CL: 3658906
4.18P3 - CL: 3676890

1. Create a new project (no template or starter content needed)
2. Save the new Level > name it "testlvl" and Build lighting so the built map data gets built
3. add a point light to the scene
4. Save the level and build lighting only
   Result: after the level is built the level becomes dirty
   Expected: The level does not become dirty