[depot_tools] Set "is_luci=False" for buildbot tests.

This is needed to change the api.runtime default to is_luci=True in
https://crrev.com/c/1750109.

R=iannucci@google.com, tandrii@google.com

Bug: 993137
Change-Id: Id52e0a12b9121d590fcb61e275eda8ca903372d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1751815
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Michael Moss <mmoss@chromium.org>

recipes/recipe_modules/git/examples/full.py

@@ -98,7 +98,10 @@ def RunSteps(api):
 
 
 def GenTests(api):
-  yield api.test('basic')
+  yield (
+    api.test('basic') +
+    api.runtime(is_luci=False, is_experimental=False)
+  )
   yield (
     api.test('basic_luci') +
     api.runtime(is_luci=True, is_experimental=False)