Fix memory doubling for density evaluation

[leila-pujal]

This PR fixes bug reported in #121 about memory doubling when calling the function evaluate_density_using_evaluated_orbs. Problematic code was condensed to avoid creating a new array which was causing the doubling in memory.

Test: Pass existing test

Checklist

• [x] Write a good description of what the PR does.
• [ ] Add tests for each unit of code added (e.g. function, class)
• [ ] Update documentation
• [ ] Squash commits that can be grouped together
• [ ] Rebase onto master

Type of Changes

	Type
✓	:bug: Bug fix

Related

[leila-pujal]

hi, I talked with @Ali-Tehrani earlier and he pointed out that condensing those lines of code does not solve the doubling memory but it is just done underhood. Despite not being output to a variable the memory is being allocated so it would be even more difficult to track down. I am closing this PR because it doesn't fix the problem.