fix: removing problematic "formattable" tag

[rusackas]

SUMMARY

Addresses a valid point in #16340 - searching for "table" is super common. "Formattable" is not a terribly useful category (I suspect) nor is it comprehensively populated it. So, I'm axing it. I'm open to other ideas :)

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue: Fixes [gallery] Remove the "Formattable" tag for chart types #16340
• 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 #24207 (a6dcb06) into master (c54eedf) will increase coverage by 0.00%.
The diff coverage is 75.00%.

❗ Current head a6dcb06 differs from pull request most recent head c38f135. Consider uploading reports for the commit c38f135 to get more accurate results

@@           Coverage Diff           @@
##           master   #24207   +/-   ##
=======================================
  Coverage   68.30%   68.30%           
=======================================
  Files        1957     1957           
  Lines       75588    75590    +2     
  Branches     8223     8223           
=======================================
+ Hits        51633    51635    +2     
  Misses      21848    21848           
  Partials     2107     2107           

Flag	Coverage Δ
javascript	54.72% <ø> (ø)

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

Impacted Files	Coverage Δ
...hart-echarts/src/BigNumber/BigNumberTotal/index.ts	66.66% <ø> (ø)
...arts/src/BigNumber/BigNumberWithTrendline/index.ts	66.66% <ø> (ø)
...t-frontend/plugins/plugin-chart-table/src/index.ts	66.66% <ø> (ø)
superset/extensions/ssh.py	67.50% <66.66%> (+0.83%)	⬆️
superset/config.py	92.00% <100.00%> (+0.02%)	⬆️

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[michael-s-molina]

LGTM