[ci] Migrate build_and_test and pull_request_stats to use arm64 runners (#94870)
A 16 core x86-64 runner is $0.042/minute. A 16 core arm64 runner is
$0.026/minute.
https://docs.github.com/en/billing/reference/actions-runner-pricing
It also looks like they're faster! After factoring the performance
improvement, this appears to be a ~50% cost reduction for migrated jobs.
Datadog SQL:
```
SELECT
REGEXP_REPLACE(ci_job_name, '\s*\([0-9]+/[0-9]+\)', '') AS ci_job_name,
labels,
branch,
commit_date,
SUM(duration) / 1000 / 1000 / 1000 / 60 as minutes,
ci_pipeline_id
FROM dd.ci_pipelines(
columns => ARRAY ['@git.commit.committer.date', '@ci.pipeline.id', '@duration', '@git.branch', '@ci.node.labels', '@ci.job.name'],
event_type => 'job',
filter => '@git.repository.id_v2:github.com/vercel/next.js @ci.pipeline.name:build-and-test @ci.provider.instance:github-actions @ci.pipeline.id:(28266192824-1 OR 28266190122-2) -@ci.job.name:*changed*',
from_timestamp => now() - INTERVAL '30 days',
to_timestamp => now()
) AS (
commit_date VARCHAR,
ci_pipeline_id VARCHAR,
duration BIGINT,
branch VARCHAR,
labels VARCHAR,
ci_job_name VARCHAR
)
GROUP BY
REGEXP_REPLACE(ci_job_name, '\s*\([0-9]+/[0-9]+\)', ''),
labels,
commit_date,
branch,
ci_pipeline_id
ORDER BY
REGEXP_REPLACE(ci_job_name, '\s*\([0-9]+/[0-9]+\)', ''),
branch,
commit_date,
minutes;
```
https://app.datadoghq.com/ddsql/editor?ddsql_dataset_id=34de66b9-30f4-48dd-ac98-354dc7e67fdf
Full Data:
https://docs.google.com/spreadsheets/d/1SszR3RsPeJ13nVW5ggMakwy87fkQMqWMHbZDehHH8IA/edit?usp=sharing
Here's the abbreviated data for jobs longer than 5 minutes:
<img width="1187" height="656" alt="Screenshot 2026-06-26 at 4 38 00 PM"
src="https://github.com/user-attachments/assets/9341039e-c4ea-405c-8d24-cdbc5ed1ba24"
/>
It seems like for the jobs switched over to arm64, they run in about
~73-82% of the time as arm.
next.js
38bd101b - [ci] Migrate build_and_test and pull_request_stats to use arm64 runners (#94870)
