fix(explore): rendering regression on standalone

[justinpark]

SUMMARY

This commit fixes the rendering regression in standalone mode(and reports) by #23778
The issue is the standalone renders the chart container only so there's no observeRef exists to initialize the chart size.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

After:
(Render a chart in a standalone)

Before:
(Empty screen)

TESTING INSTRUCTIONS

Go to any chart explore link
Add &standalone=true parameter at the end

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

[eschutho]

LGTM!

[codecov]

Codecov Report

Merging #24177 (8113d88) into master (455e23b) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 8113d88 differs from pull request most recent head 6157d15. Consider uploading reports for the commit 6157d15 to get more accurate results

@@            Coverage Diff             @@
##           master   #24177      +/-   ##
==========================================
+ Coverage   68.27%   68.28%   +0.01%     
==========================================
  Files        1955     1955              
  Lines       75451    75451              
  Branches     8215     8215              
==========================================
+ Hits        51511    51522      +11     
+ Misses      21834    21825       -9     
+ Partials     2106     2104       -2     

Flag	Coverage Δ
javascript	54.70% <100.00%> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
...src/explore/components/ExploreChartPanel/index.jsx	77.63% <100.00%> (+7.89%)	⬆️

... and 3 files with indirect coverage changes

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[sadpandajoe]

🏷️ preset:2023.21