ci(release): raise dockerd max-concurrent-uploads for release publish

max-concurrent-uploads is a daemon-wide limit shared by every image
push. Releases now push to all registries and several directories at
once, so the default of 5 would queue dozens of concurrent pushes
behind 5 upload slots.

Add hack/set-docker-max-concurrent-uploads.sh, which sets the value in
/etc/docker/daemon.json, keeps any other keys, and reloads dockerd with
SIGHUP (the option can be changed live), and run it with 20 in the
release pipeline.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Release v3.33.0

build: v1.43.1 release (#5291)

build: v3.32.2 release (#13673)

* build: v3.32.2 release
* Parallelize more post-release tests

build: v1.42.6 release (#5275)

build: v1.42.5 release (#5258)

[release-v1.40] Auto Release Update for v1.40.15 (#5235)

Add release notes

[release-v1.40] Auto Release Update for v1.40.14 (#5218)

Begin development on v1.45.0