Clarify log messages in controller package

[antoineco]

What this PR does / why we need it:

This is an attempt to clarify most messages logged by the controller package and add details when I felt it was necessary (eg. what object a given message is related to, or why do we default to a particular value)

I also took the liberty of rephrasing some methods documentation as I went through the code, and to remove comments where the logic is self-explanatory.

See #2368 (comment)

Cherry-picked examples:

controller.go:922] Ingress "nginx/examples" defines both a backend and rules. Using backend as default upstream for all its rules.
controller.go:1002] Ingress "nginx/examples" does not contains a TLS section.
controller.go:461] Adding location "/foo1" for server "host1" with upstream "nginx-echoheaders2-http" (Ingress "nginx/examples")
controller.go:461] Adding location "/foo2" for server "host1" with upstream "nginx-echoheaders2-http" (Ingress "nginx/examples")
controller.go:209] Obtaining information about TCP stream services from ConfigMap "nginx/tcp-services"
controller.go:289] Searching Endpoints with TCP port name "http" for Service "nginx/echoheaders"

[antoineco]

/assign @aledbf
/assign @ElvinEfendi

[aledbf]

/approve
/lgtm

[antoineco]

/hold
I need to adjust some E2E strings.

[antoineco]

/hold cancel
done

[codecov-io]

Codecov Report

Merging #2639 into master will increase coverage by 0.11%.
The diff coverage is 9.23%.

@@            Coverage Diff             @@
##           master    #2639      +/-   ##
==========================================
+ Coverage   40.72%   40.83%   +0.11%     
==========================================
  Files          75       75              
  Lines        5120     5123       +3     
==========================================
+ Hits         2085     2092       +7     
+ Misses       2753     2750       -3     
+ Partials      282      281       -1

Impacted Files	Coverage Δ
internal/ingress/controller/tcp.go	0% <0%> (ø)	⬆️
internal/ingress/controller/controller.go	2.21% <0%> (-0.02%)	⬇️
internal/ingress/controller/endpoints.go	94.23% <100%> (ø)	⬆️
internal/ingress/controller/nginx.go	11.26% <3.03%> (+0.02%)	⬆️
internal/ingress/controller/util.go	41.66% <50%> (ø)	⬆️
cmd/nginx/main.go	29% <0%> (+5.34%)	⬆️

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[aledbf]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [aledbf]

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[ElvinEfendi]

Is new a more (in comparison to &) standard way of initializing objects in Go? Is it doing something different than & in this specific case?

[antoineco]

new is pretty much equivalent to &Type{}, it allocates memory for the given Type. I like to use it for initializing zero values, but it's mostly sugar.

[ElvinEfendi]

love these changes!