fix(vipergc-660): identify axis keys upon adding object to composition

[ozyx]

Closes VIPERGC-660

Describe your changes:

Fixes an issue causing Graphs to not plot any data until the "Config" inspector tab was opened.

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Author Checklist

• Changes address original issue?
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[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 6 lines in your changes missing coverage. Please review.

Project coverage is 57.44%. Comparing base (3e23dce) to head (6777c76).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/plugins/charts/bar/BarGraphView.vue	57.14%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7897      +/-   ##
==========================================
+ Coverage   57.12%   57.44%   +0.31%     
==========================================
  Files         676      676              
  Lines       27357    27370      +13     
  Branches     2685     2688       +3     
==========================================
+ Hits        15627    15722      +95     
+ Misses      11392    11308      -84     
- Partials      338      340       +2     

Flag	Coverage Δ
e2e-ci	62.47% <ø> (+<0.01%)	⬆️
e2e-full	41.80% <ø> (+18.34%)	⬆️
unit	49.30% <57.14%> (+0.02%)	⬆️

Files with missing lines	Coverage Δ
src/plugins/charts/bar/BarGraphView.vue	62.84% <57.14%> (+2.25%)	⬆️

... and 7 files with indirect coverage changes

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[shefalijoshi]

One small change.

[shefalijoshi]

The yKey is irrelevant when we're using nonArrayValues. Change this to:
yKey = 'none';

[shefalijoshi]

Approving - please make the change and merge.