This is preparatory work towards adding a Topic model.
We plan to use the local variable name as 'topic' for
the Topic model objects.
Currently, we use *topic as the local variable name for
topic names.
We rename local variables of the form *topic to *topic_name
so that we don't need to think about type collisions in
individual code paths where we might want to talk about both
Topic objects and strings for the topic name.
This is a follow up to #24673, we want to modify every webhook
events to follow the same pattern and consistency where branch name
should only show on opened and merged events.
7 characters are not enough for large projects, so we change
it to reasonably longer. As an example, The Linux kernel needs
at least 11 characters of sha in its shortened form to identify
a revision. We pick 11 so it should work for most of the projects.
Signed-off-by: Zixuan James Li <p359101898@gmail.com>