chore: add a job that check that all other jobs are green on PR (#13217)

## Changes 

* Enable Green CI Policy on dd-trace-py
* on label change, some check can become green -> exclude change log
check, as it's already required
* on PR check list, some PR can become green -> exclude checklist check,
as it's already required
* concurrency


This does not enforce checks on gitlab, for those, the required check on
`dd-gitlab/default-pipeline` do the trick (eventually completed by other
if needed).


## Change

Added a job that verify the status of other jobs on the PR: 

* If one of those jobs is pending, running or failed, this job fails.
* Once all jobs are finished in success, it succeed.

The next step, once we've validated it works correctly, is to make this
job a requirement for merges. Side note, this solution has been
[implemented](https://github.com/DataDog/dd-trace-js/blob/master/.github/workflows/all-green.yml)
successfully on DataDog/dd-trace-js for one year.

I've removed `Bootstrap import analysis` from this check because it 20
PR has been merged with this job failing over the 195 PR on the last 60
days (success rate of 88%). Once this job is considered as healthy (or
if we want to enforce it) we can remove it.

There are other jobs with a bad success rate, but they are not often
included in PR, so TBD. Here are the jobs with a success rate lower than
95% :

  * 95% (104) test
  * 95% (187) dd-gitlab/check_pipeline_status
  * 93% (30) dd-gitlab/contrib::dd_trace_api 1/4
  * 93% (30) dd-gitlab/contrib::dd_trace_api 2/4
  * 93% (30) dd-gitlab/contrib::dd_trace_api 3/4
  * 93% (30) dd-gitlab/contrib::dd_trace_api 4/4
  * 92% (200) dd-gitlab/default-pipeline
  * 88% (195) Bootstrap import analysis
  * 62% (8) dd-gitlab/contrib::dd_trace_api 1/1
  * 0% (9) CircleCI Pipeline


## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Author: cbeauchesne

.github/workflows/all-green.yml

@@ -0,0 +1,30 @@
+name: All Green
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  all-green:
+    runs-on: ubuntu-latest
+    permissions:
+      checks: read
+      contents: read
+    steps:
+      - uses: wechuli/allcheckspassed@e22f45a4f25f4cf821d1273705ac233355400db1
+        with:
+          delay: 10  # wait for this delay before starting
+          polling_interval: 1 # after a failure, how long do it wait before checking again
+          retries: 60  # how many retries before stopping 
+          checks_exclude: 'Bootstrap import analysis,require-checklist,Validate changelog'
+
+# Why some checks are excluded?
+#
+# - Bootstrap import analysis: TO BE ADDED (Success rate of 88% as of 2025-04-17)
+# - require-checklist: this job is triggered by a change on PR description, and already explcititly required
+# - Validate changelog: this job is triggered by a change on labels, and already explcititly required