Enable and fix carbon and graphite docker integration test

[robskillington]

This also updates the carbon ingester configuration to match the default M3 ingester config where if the config is not nil, then it is used, otherwise it's not. This removes the enabled field which was rather different to how the M3 ingester config's presence or absence defines whether to use it or not.

[codecov]

Codecov Report

Merging #1319 into master will increase coverage by <.1%.
The diff coverage is 33.3%.

@@           Coverage Diff            @@
##           master   #1319     +/-   ##
========================================
+ Coverage    70.6%   70.6%   +<.1%     
========================================
  Files         811     811             
  Lines       68966   68960      -6     
========================================
+ Hits        48699   48719     +20     
+ Misses      17133   17110     -23     
+ Partials     3134    3131      -3

Flag	Coverage Δ
#aggregator	80.9% <ø> (ø)	⬆️
#cluster	85.6% <ø> (ø)	⬆️
#collector	78.4% <ø> (ø)	⬆️
#dbnode	80.9% <ø> (ø)	⬆️
#m3em	73.2% <ø> (ø)	⬆️
#m3ninx	74.6% <ø> (-0.1%)	⬇️
#m3nsch	51.1% <ø> (ø)	⬆️
#metrics	17.8% <ø> (ø)	⬆️
#msg	75% <ø> (+0.1%)	⬆️
#query	64% <33.3%> (ø)	⬆️
#x	75.9% <ø> (ø)	⬆️

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