[MIRROR] Gets rid of UNIT_TESTS compiler warning (#2077)

* Gets rid of UNIT_TESTS compiler warning (#82695)

## About The Pull Request

Basically every single CI Run is throwing the following warning:
```txt
code/modules/unit_tests/lootpanel.dm:24:warning (unused_var): new_box: variable defined but not used
```

You may find an example here:
https://github.com/tgstation/tgstation/actions/runs/8698627681/job/23855921813#step:9:24

This is pretty silly but I don't really know why we even have this
variable (I assume there's something far more complicated underneath the
surface based on what the unit test is asserting), but assuming it is
important let's just insert a do-nothing procedure to get rid of the
compiler warning while ensuring the unit test is actually operating as
it should.

I also don't really like the fact that this is a warning instead of an
error but let's tackle this problem one step at a time by at least
getting rid of the compiler warning in a quick advance PR while I dwell
on this issue (is there a way to get the Dreamchecker linter to look at
the unit test files? it's caught perfectly fine in the langserver)

---------

Co-authored-by: MrMelbert <[email protected]>

* Gets rid of UNIT_TESTS compiler warning

---------

Co-authored-by: san7890 <[email protected]>
Co-authored-by: MrMelbert <[email protected]>

code/modules/unit_tests/lootpanel.dm

@@ -21,7 +21,7 @@
 	TEST_ASSERT_EQUAL(length(panel.contents), 1, "Contents should update on searchobj deleted")
 	TEST_ASSERT_EQUAL(length(panel.to_image), 1, "to_image should update on searchobj deleted")
 
-	var/obj/item/storage/toolbox/new_box = allocate(/obj/item/storage/toolbox, one_over)
+	allocate(/obj/item/storage/toolbox, one_over)
 	TEST_ASSERT_EQUAL(length(panel.contents), 1, "Contents shouldn't update, we're dumb")
 	TEST_ASSERT_EQUAL(length(panel.to_image), 1, "to_image shouldn't update, we're dumb")
 
@@ -32,3 +32,4 @@
 	TEST_ASSERT_EQUAL(length(panel.contents), 2, "Panel shouldnt dupe searchables if reopened")
 
 	mock_client.mob = null
+