Bug 1637354: Don't show time estimates for |./mach try release| r=ahal

Mach doesn't know which tasks are part of a release - that's decided in the decision task. Instead of
showing a bogus estimation, we shouldn't show one at all.

Differential Revision: https://phabricator.services.mozilla.com/D74904

tools/tryselect/push.py

@@ -143,7 +143,7 @@ def push_to_try(method, msg, try_task_config=None,
                 push=True, closed_tree=False, files_to_change=None):
     check_working_directory(push)
 
-    if try_task_config and method not in ('auto', 'empty'):
+    if try_task_config and method not in ('auto', 'empty', 'release'):
         display_push_estimates(try_task_config)
 
     # Format the commit message