Fix error setting $service_name NGINX variable

[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

fixes #5515

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.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf

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• OWNERS [aledbf]

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[codecov-io]

Codecov Report

Merging #5536 into master will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #5536      +/-   ##
==========================================
- Coverage   58.56%   58.54%   -0.02%     
==========================================
  Files          88       88              
  Lines        6948     6950       +2     
==========================================
  Hits         4069     4069              
- Misses       2431     2432       +1     
- Partials      448      449       +1     

Impacted Files	Coverage Δ
internal/ingress/controller/template/template.go	79.67% <0.00%> (-0.22%)	⬇️

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[ElvinEfendi]

Where did the regression got introduced?

[aledbf]

Where did the regression got introduced?

Check the issue #5515

[aledbf]

@ElvinEfendi just in case this issue only happens when the $service_name variable is used to route traffic, like using linkerd.

[aledbf]

/retest

[aledbf]

/retest

[aledbf]

/assign @ElvinEfendi

[aledbf]

/retest