Add ciflow config and change jinja2 templates (#61886)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61886
This PR is rolling out at the `1. Manual Phase`.
```
# Rollout Strategy:
# 1. Manual Phase
# step 1. Add 'ciflow/default' label to the PR
# step 2. Once there's an [unassigned] event from PR, it should rerun
# step 3. Remove 'ciflow/default' label
# step 4. Trigger the [unassigned] event again, it should not rerun
# 2. Probot Phase 1 (manual on 1 workflow)
# step 1. Probot automatically add labels based on the context
# step 2. Manually let probot trigger [unassigned] event
# 4. Probot Phase 3 (auto on 1 workflows)
# step 1. Modify the workflows so that they only listen on [unassigned] events
# step 2. Probot automatically adds labels automatically based on the context
# step 3. Probot automatically triggers [unassigned] event
# 4. Probot Phase 3 (auto on many workflows)
# step 1. Enable it for all workflows
```
Test Plan: Imported from OSS
Reviewed By: seemethere
Differential Revision: D29808366
Pulled By: zhouzhuojie
fbshipit-source-id: c7e5009d839239df58825dec093ff0f1fd281697
