fix auto hide legend padding

[lessmost]

Checklist

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

Description of change

1. 调整坐标轴标签默认的 autoHide 配置，默认开启 autoHide，并设置最小间距 6px

before	after

2. 调整图例的默认 padding，使得图例和图形对齐
   • 可通过主题分别对水平布局的图例和垂直布局的图例分别配置 padding
   • 默认的 light/dark 主题设置合适的 padding

before	after

[github-actions]

😭 Deploy PR Preview e64bc5f failed. Build logs

_{🤖 By surge-preview}

[coveralls]

Pull Request Test Coverage Report for Build 413046297

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 7 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.07%) to 93.374%

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

Totals
Change from base Build 410134101:	-0.07%
Covered Lines:	10673
Relevant Lines:	11084

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💛 - Coveralls

[hustcc]

Axis label 默认间距多少？

[lessmost]

Axis label 默认间距多少？

6px