Build multi-arch images by default

[aledbf]

What this PR does / why we need it:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Which issue/s this PR fixes

How Has This Been Tested?

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added tests to cover my changes.
• All new and existing tests passed.

[aledbf]

/hold

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [aledbf]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov-commenter]

Codecov Report

Merging #5629 into master will decrease coverage by 0.06%.
The diff coverage is 39.53%.

@@            Coverage Diff             @@
##           master    #5629      +/-   ##
==========================================
- Coverage   58.54%   58.48%   -0.07%     
==========================================
  Files          88       88              
  Lines        6950     6975      +25     
==========================================
+ Hits         4069     4079      +10     
- Misses       2432     2446      +14     
- Partials      449      450       +1     

Impacted Files	Coverage Δ
cmd/nginx/main.go	5.61% <0.00%> (-0.38%)	⬇️
...ternal/ingress/annotations/sessionaffinity/main.go	60.41% <ø> (+1.59%)	⬆️
internal/ingress/controller/template/template.go	79.67% <0.00%> (ø)
internal/ingress/types.go	0.00% <ø> (ø)
internal/ingress/types_equals.go	17.09% <0.00%> (-0.10%)	⬇️
internal/ingress/controller/controller.go	49.59% <42.85%> (-0.06%)	⬇️
internal/ingress/annotations/annotations.go	81.69% <100.00%> (ø)
internal/ingress/annotations/sslcipher/main.go	100.00% <100.00%> (ø)
internal/task/queue.go	77.92% <0.00%> (-2.60%)	⬇️

---

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[aledbf]

/test pull-ingress-nginx-e2e-1-17

[aledbf]

/test pull-ingress-nginx-e2e-1-16

[aledbf]

/test pull-ingress-nginx-e2e-1-15

[aledbf]

/hold cancel