fix takeScreenshot for display_id, change double flash launch to one flash

[codeskyblue]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 28.20513% with 28 lines in your changes missing coverage. Please review.

Project coverage is 25.39%. Comparing base (4157409) to head (d62f1df).

Files	Patch %	Lines
uiautomator2/utils.py	18.75%	13 Missing ⚠️
uiautomator2/core.py	25.00%	9 Missing ⚠️
uiautomator2/__init__.py	33.33%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #996      +/-   ##
==========================================
- Coverage   25.39%   25.39%   -0.01%     
==========================================
  Files          20       20              
  Lines        2863     2879      +16     
  Branches      443      446       +3     
==========================================
+ Hits          727      731       +4     
- Misses       2111     2122      +11     
- Partials       25       26       +1     

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