Fix wrong default value for enable-brotli

[webwurst]

Brotli is disabled by default since c67e918.

[aledbf]

/approve
/lgtm

[aledbf]

@webwurst thanks!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[codecov-io]

Codecov Report

Merging #2566 into master will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2566      +/-   ##
==========================================
+ Coverage   40.63%   40.69%   +0.05%     
==========================================
  Files          74       74              
  Lines        5094     5094              
==========================================
+ Hits         2070     2073       +3     
+ Misses       2743     2741       -2     
+ Partials      281      280       -1

Impacted Files	Coverage Δ
cmd/nginx/main.go	25.95% <0%> (+2.29%)	⬆️

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