fix(area-shape): fix marker fillOpacity

[itiiss]

Checklist

• [✅ ] npm test passes
• [ ✅] tests and/or benchmarks are included
• [✅ ] commit message follows commit guidelines

Description of change

before	after

area-area 和 area-smooth 这两种内置shape的默认getMarker没有初始的的fillOpacity值，导致使用了默认主题中areaFillOpacity=0.25的值
fixed #3123

[coveralls]

Pull Request Test Coverage Report for Build 2587567875

Warning: This coverage report may be inaccurate.

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A quick fix for this PR: rebase it; your next report should be accurate.

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 7 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.05%) to 91.271%

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Files with Coverage Reduction	New Missed Lines	%
src/chart/controller/gesture.ts	7	82.14%

Totals
Change from base Build 2582561281:	-0.05%
Covered Lines:	11820
Relevant Lines:	12458

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💛 - Coveralls

[github-actions]

🎊 PR Preview 9789742 has been successfully built and deployed to https://antvis-G2-preview-pr-4017.surge.sh?type=diff&date=2022-07-04

🕐 Build time: 69.372s

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