Remove Show* TLS configs

[albertteoh]

Signed-off-by: albertteoh albert.teoh@logz.io

Which problem is this PR solving?

• Resolves Removing Show* TLS config flags #3104.

Short description of the changes

• Removes the redundant Show* TLS config flags, which appear to all be true and don't seem to have changed for months (in some cases, years) since its introduction, and cannot see evidence where this could be changed by users via config parameters; i.e. it can only be changed in code.
• If there is still a use case for keeping these flags, please advise and I suggest we document these reasons in a sensible place somewhere in code.

[codecov]

Codecov Report

Merging #3106 (d323bab) into master (4af24f2) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3106      +/-   ##
==========================================
- Coverage   95.94%   95.92%   -0.02%     
==========================================
  Files         236      236              
  Lines       10251    10238      -13     
==========================================
- Hits         9835     9821      -14     
- Misses        345      346       +1     
  Partials       71       71              

Impacted Files	Coverage Δ
cmd/agent/app/reporter/grpc/flags.go	100.00% <ø> (ø)
cmd/collector/app/builder_flags.go	100.00% <ø> (ø)
cmd/query/app/flags.go	100.00% <ø> (ø)
pkg/config/tlscfg/flags.go	100.00% <100.00%> (ø)
plugin/metrics/prometheus/options.go	100.00% <100.00%> (ø)
plugin/storage/cassandra/options.go	100.00% <100.00%> (ø)
plugin/storage/es/options.go	100.00% <100.00%> (ø)
plugin/storage/integration/integration.go	77.34% <0.00%> (-0.56%)	⬇️

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