Rename zuul-launcher to zuul-executor

To avoid confusion with nodepool-launcher, we've decided to rename
zuul-launcher to zuul-executor.

Change-Id: I7d03cf0f0093400f4ba2e4beb1c92694224a3e8c
Signed-off-by: Paul Belanger <pabelanger@redhat.com>
diff --git a/tests/unit/test_cloner.py b/tests/unit/test_cloner.py
index da0f774..e65904b 100644
--- a/tests/unit/test_cloner.py
+++ b/tests/unit/test_cloner.py
@@ -610,7 +610,7 @@
 
         # Start a periodic job
         self.worker.hold_jobs_in_build = True
-        self.launcher.negative_function_cache_ttl = 0
+        self.executor.negative_function_cache_ttl = 0
         self.config.set('zuul', 'layout_config',
                         'tests/fixtures/layout-timer.yaml')
         self.sched.reconfigure(self.config)