fix: remove variables from styled component

[pkdotson]

SUMMARY

This pr remove less vars from styled component in the dashboard builder and hovermenu

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Screen.Recording.2021-10-25.at.9.36.15.PM.mov

TESTING INSTRUCTIONS

Go to dashboard builder and check that styles are applied when user hovers over row within and column or row within tabs.

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 #17228 (7cbbca4) into master (ef01cbb) will increase coverage by 0.14%.
The diff coverage is 95.14%.

❗ Current head 7cbbca4 differs from pull request most recent head 43cc98b. Consider uploading reports for the commit 43cc98b to get more accurate results

@@            Coverage Diff             @@
##           master   #17228      +/-   ##
==========================================
+ Coverage   76.82%   76.97%   +0.14%     
==========================================
  Files        1038     1037       -1     
  Lines       55597    55635      +38     
  Branches     7585     7594       +9     
==========================================
+ Hits        42715    42825     +110     
+ Misses      12632    12560      -72     
  Partials      250      250              

Flag	Coverage Δ
javascript	71.03% <94.94%> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
superset-frontend/src/components/Select/Select.tsx	92.35% <ø> (ø)
...nd/src/dashboard/components/nativeFilters/types.ts	100.00% <ø> (ø)
...perset-frontend/src/explore/components/Control.tsx	76.47% <ø> (ø)
...tend/src/explore/components/ExploreChartHeader.jsx	6.84% <0.00%> (-0.20%)	⬇️
...nts/controls/ConditionalFormattingControl/types.ts	100.00% <ø> (ø)
...ontend/src/filters/components/Select/buildQuery.ts	100.00% <ø> (ø)
superset-frontend/src/setup/setupColors.ts	100.00% <ø> (ø)
superset/annotation_layers/schemas.py	100.00% <ø> (ø)
...Filters/FilterBar/FilterControls/FilterControl.tsx	94.87% <88.88%> (-5.13%)	⬇️
...et-frontend/src/dashboard/components/Dashboard.jsx	81.88% <100.00%> (+3.79%)	⬆️
... and 19 more

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[geido]

@pkdotson it appears you might have some to remove from this file too superset-frontend/src/dashboard/components/menu/HoverMenu.tsx. Thanks!