feat(chart): adjust chartclient to point to new endpoints

[kristw]

🐛 Bug Fix

Update according to the new endpoints.

[vercel]

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[williaster]

nice! lgtm

[codecov]

Codecov Report

Merging #551 into master will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #551      +/-   ##
==========================================
- Coverage   23.14%   23.13%   -0.02%     
==========================================
  Files         290      290              
  Lines        6784     6783       -1     
  Branches      676      676              
==========================================
- Hits         1570     1569       -1     
  Misses       5176     5176              
  Partials       38       38              

Impacted Files	Coverage Δ
...kages/superset-ui-chart/src/clients/ChartClient.ts	100.00% <100.00%> (ø)

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