fix(examples): Cleanup dashboard filter scopes

[john-bodley]

SUMMARY

Legacy filter scope are keyed by the column name (unique to a given filter-box chart) rather than the optional (and potentially non-unique) label (or similar).

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

CI.

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #23260 (23d2e3b) into master (1f3eb56) will increase coverage by 0.01%.
The diff coverage is 75.82%.

❗ Current head 23d2e3b differs from pull request most recent head fb61ce6. Consider uploading reports for the commit fb61ce6 to get more accurate results

@@            Coverage Diff             @@
##           master   #23260      +/-   ##
==========================================
+ Coverage   67.51%   67.53%   +0.01%     
==========================================
  Files        1907     1909       +2     
  Lines       73435    73488      +53     
  Branches     7977     7987      +10     
==========================================
+ Hits        49579    49629      +50     
- Misses      21804    21809       +5     
+ Partials     2052     2050       -2     

Flag	Coverage Δ
hive	52.77% <83.01%> (+0.04%)	⬆️
mysql	78.44% <98.11%> (+0.02%)	⬆️
postgres	78.50% <98.11%> (+0.02%)	⬆️
presto	52.70% <83.01%> (+0.06%)	⬆️
python	82.28% <98.11%> (+0.02%)	⬆️
sqlite	76.98% <98.11%> (+0.02%)	⬆️
unit	52.49% <26.41%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...et-ui-chart-controls/src/operators/sortOperator.ts	100.00% <ø> (ø)
...rt-controls/src/shared-controls/customControls.tsx	17.39% <0.00%> (-7.61%)	⬇️
...s/plugin-chart-pivot-table/src/PivotTableChart.tsx	0.00% <0.00%> (ø)
...tend/plugins/plugin-chart-table/src/TableChart.tsx	45.16% <0.00%> (-0.25%)	⬇️
...rontend/src/dashboard/containers/DashboardPage.tsx	8.79% <0.00%> (-0.10%)	⬇️
superset/common/query_context_processor.py	88.47% <ø> (ø)
superset/models/helpers.py	38.16% <66.66%> (+0.13%)	⬆️
.../plugin-chart-echarts/src/Timeseries/buildQuery.ts	70.00% <75.00%> (-1.43%)	⬇️
...t-ui-chart-controls/src/operators/pivotOperator.ts	100.00% <100.00%> (ø)
...ontrols/src/operators/utils/extractExtraMetrics.ts	100.00% <100.00%> (ø)
... and 15 more

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