Use docker buildx for release image

[saschagrunert]

1. Why is this pull request needed and what does it do?

This allows to choose the correct architecture in the image manifest,
which defaulted to the host system before applying this patch.

2. Which issues (if any) are related?

Refers to kubernetes/kubernetes#104085

3. Which documentation changes (if any) need to be made?

None

4. Does this introduce a backward incompatible change or deprecation?

Fixed architecture within manifest for non amd64 images.

[dims]

cc @johnbelamaric

[codecov-commenter]

Codecov Report

Merging #4779 (b5d5a83) into master (93c57b6) will decrease coverage by 0.33%.
The diff coverage is 61.13%.

@@            Coverage Diff             @@
##           master    #4779      +/-   ##
==========================================
- Coverage   55.70%   55.36%   -0.34%     
==========================================
  Files         224      232       +8     
  Lines       10016    14367    +4351     
==========================================
+ Hits         5579     7954    +2375     
- Misses       3978     5918    +1940     
- Partials      459      495      +36     

Impacted Files	Coverage Δ
core/dnsserver/address.go	100.00% <ø> (ø)
core/dnsserver/config.go	0.00% <ø> (ø)
core/dnsserver/onstartup.go	0.00% <0.00%> (ø)
core/dnsserver/server.go	34.69% <0.00%> (+8.37%)	⬆️
plugin/auto/auto.go	0.00% <0.00%> (ø)
plugin/auto/zone.go	78.94% <ø> (+0.68%)	⬆️
plugin/backend_lookup.go	0.00% <0.00%> (ø)
plugin/bind/bind.go	50.00% <0.00%> (-50.00%)	⬇️
plugin/etcd/etcd.go	0.00% <ø> (ø)
plugin/etcd/setup.go	1.14% <0.00%> (-0.26%)	⬇️
... and 290 more

---

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[johnbelamaric]

/approve
/merge

@chrisohaver @miekg
@saschagrunert I assume this means our published manifests are wrong today?

[dims]

@johnbelamaric unfortunately some of the arch(es) are wrong, kubernetes/kubernetes#104085 has some details.

[saschagrunert]

Yes the issue should mainly affect the manifests for the non amd64 bit images, while the binaries within the images are correct.

[miekg]

fyi: this change has been reverted because it broke the docker build.

if something like this is still needed, it cannot assume binfmt kernel module is loaded and it should not run a privileged docker container