fix wrong config generation when upstream-hash-by is set

[ElvinEfendi]

What this PR does / why we need it:
fixes incorrect config generation when upstream-hash-by is set.

An incorrectly generated config looks like:

    upstream squawk-production-squawk-web-80 {
        hash {{ $upstream.UpstreamHashBy }} consistent;

        keepalive 32;

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

[codecov-io]

Codecov Report

Merging #2215 into master will increase coverage by 0.14%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #2215      +/-   ##
==========================================
+ Coverage   36.98%   37.12%   +0.14%     
==========================================
  Files          70       70              
  Lines        4978     4978              
==========================================
+ Hits         1841     1848       +7     
+ Misses       2857     2851       -6     
+ Partials      280      279       -1

Impacted Files	Coverage Δ
internal/ingress/controller/template/template.go	64.33% <0%> (ø)	⬆️
cmd/nginx/main.go	26.2% <0%> (+4.82%)	⬆️

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[aledbf]

/approve

[aledbf]

@ElvinEfendi thanks!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, ElvinEfendi

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