fix: Remove "required" from SaveModal Add to dashboard field

[kgabryje]

SUMMARY

Remove an asterisk from SaveModal, which indicated that Add to dashboard field is required.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TEST PLAN

ADDITIONAL INFORMATION

• Has associated issue: "Add to Dashboard" in Save Chart modal should not be a required field #11468
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

CC: @ktmud

[codecov-io]

Codecov Report

Merging #11693 (af773c1) into master (2f036e9) will increase coverage by 4.12%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #11693      +/-   ##
==========================================
+ Coverage   62.85%   66.98%   +4.12%     
==========================================
  Files         889      889              
  Lines       43053    43061       +8     
  Branches     4015     4015              
==========================================
+ Hits        27063    28844    +1781     
+ Misses      15812    14115    -1697     
+ Partials      178      102      -76     

Flag	Coverage Δ
cypress	56.09% <ø> (?)
javascript	62.82% <ø> (ø)
python	62.87% <ø> (ø)

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

Impacted Files	Coverage Δ
...rset-frontend/src/explore/components/SaveModal.jsx	95.58% <ø> (+4.41%)	⬆️
...et-frontend/src/SqlLab/components/LimitControl.tsx	89.36% <0.00%> (-1.95%)	⬇️
...-frontend/src/datasource/ChangeDatasourceModal.tsx	74.24% <0.00%> (-1.15%)	⬇️
...ntend/src/views/CRUD/annotation/AnnotationList.tsx	77.17% <0.00%> (-0.85%)	⬇️
...ews/CRUD/annotationlayers/AnnotationLayerModal.tsx	73.03% <0.00%> (-0.83%)	⬇️
...t-frontend/src/views/CRUD/welcome/SavedQueries.tsx	58.62% <0.00%> (-0.69%)	⬇️
...tend/src/views/CRUD/annotation/AnnotationModal.tsx	66.14% <0.00%> (-0.53%)	⬇️
.../src/components/dataViewCommon/TableCollection.tsx	100.00% <0.00%> (ø)
superset-frontend/src/views/CRUD/utils.tsx	50.00% <0.00%> (+1.21%)	⬆️
...rontend/src/SqlLab/components/AceEditorWrapper.tsx	60.75% <0.00%> (+1.26%)	⬆️
... and 169 more

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[rusackas]

@kgabryje a rebase will likely fix the failing cypress flakage.