fix http response header (#2924)

[logeable]

Which problem is this PR solving?

• Resolve The response ContentType of HealthCheck.Handler is not application/json #2924

Short description of the changes

[codecov]

Codecov Report

Merging #2925 (0d6afec) into master (33e8e96) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2925      +/-   ##
==========================================
+ Coverage   95.91%   95.97%   +0.06%     
==========================================
  Files         223      223              
  Lines        9708     9708              
==========================================
+ Hits         9311     9317       +6     
+ Misses        327      324       -3     
+ Partials       70       67       -3     

Impacted Files	Coverage Δ
pkg/healthcheck/handler.go	100.00% <100.00%> (ø)
plugin/storage/integration/integration.go	77.34% <0.00%> (-0.56%)	⬇️
plugin/storage/badger/spanstore/reader.go	96.08% <0.00%> (+0.71%)	⬆️
cmd/query/app/server.go	97.08% <0.00%> (+1.45%)	⬆️
cmd/query/app/static_handler.go	96.77% <0.00%> (+1.61%)	⬆️
cmd/collector/app/server/zipkin.go	76.92% <0.00%> (+3.84%)	⬆️

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[yurishkuro]

Thanks!

In the future, please add Resolve #1234 to the description to link & close the respective ticket.

[yurishkuro]

@Ashmita152 this is an interesting example where many GH actions fail because the source branch of the fork is also master, and it's confusing the scripts into thinking they need to do Docker release as if it was on real master.

[yurishkuro]

@logeable do you mind re-creating this PR from a named branch in your fork? In general, I do not recommend doing PRs from master even in your own fork, it's best to keep master in sync with upstream.

[logeable]

Thanks!

In the future, please add Resolve #1234 to the description to link & close the respective ticket.

Thanks for reminding.

[logeable]

@logeable do you mind re-creating this PR from a named branch in your fork? In general, I do not recommend doing PRs from master even in your own fork, it's best to keep master in sync with upstream.

Ok, I'll create a new pr.