Add the namespace to the series limit error

[ryanhall07]

This should help in understanding why a query exceeded the series limit.
Options are:

1. exceeded in a single database instance. the error is returned from
   the db.
2. exceeded within a single namespace after summing the results from
   every database.
3. exceeded when adding the results from a namespace to the existing
   results from previous namespaces.

What this PR does / why we need it:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing and/or backwards incompatible change?:

Does this PR require updating code package or user-facing documentation?:

[codecov]

Codecov Report

Merging #3519 (3e96cb7) into master (3e96cb7) will not change coverage.
The diff coverage is n/a.

❗ Current head 3e96cb7 differs from pull request most recent head 52cb1b4. Consider uploading reports for the commit 52cb1b4 to get more accurate results

@@          Coverage Diff           @@
##           master   #3519   +/-   ##
======================================
  Coverage    55.9%   55.9%           
======================================
  Files         548     548           
  Lines       61378   61378           
======================================
  Hits        34350   34350           
  Misses      23921   23921           
  Partials     3107    3107           

Flag	Coverage Δ
aggregator	57.3% <0.0%> (ø)
cluster	∅ <0.0%> (∅)
collector	54.3% <0.0%> (ø)
dbnode	60.3% <0.0%> (ø)
m3em	46.4% <0.0%> (ø)
metrics	19.8% <0.0%> (ø)
msg	74.6% <0.0%> (ø)

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