Port --ci switch into bump-oss-version.js and remove superfluous --testing switch.

[tom-un]

Please select one of the following

• I am removing an existing difference between facebook/react-native and microsoft/react-native-macos 👍
• I am cherry-picking a change from Facebook's react-native into microsoft/react-native-macos 👍
• I am making a fix / change for the macOS implementation of react-native
• I am making a change required for Microsoft usage of react-native

Summary

The bump-oss-version.js script is used during npm publishing and during PR testing of the react-native-macos-init command line tool. Both the canary builds and the PR test use the --nightly switch which rename the package version to 0.0.0-<commithash>.

A version number of all zeros in a .podspec causes pod install to fail, so in 0.62-stable branch a --ci switch was added that changes the version to the passed in string and react-native-macos-init.yml passes in 0.62.1000 (#596). In a recent PR to master (#603), I made a similar but different fix to add a --testing flag that uses the version 1000.0.0 not realizing that this fix was already in the 0.62-stable branch.

This PR removes that script changes I made in #603 and replaces them with the fixes already made in 0.62-stable by #596.

Changelog

[macOS] [fixed] - Port --ci switch into bump-oss-version.js and remove superfluous --testing switch.

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[pull-bot]

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