Fix markdown hyperlinks in the style guide (#150071)

Some of the syntax in the migrated [style guide](https://github.com/flutter/flutter/blob/14df7be3f9471a97f34e4601fb7710850373ac3b/docs/contributing/Style-guide-for-Flutter-repo.md#lazy-programming) (and "workarounds for common issues") doesn't show up super well as a `.md` file on GitHub. (related: #145009)

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#### Current

> You may hear team members say "embrace the http://www.catb.org/jargon/html/Y/yak-shaving.html[yak
shave]!". This is an encouragement to https://www.youtube.com/watch?v=AbSehcT19u0[take on the larger effort necessary] to perform a proper fix for a problem rather than just applying a band-aid.

#### This PR

> You may hear team members say "embrace the [yak shave](http://www.catb.org/jargon/html/Y/yak-shaving.html)!". This is an encouragement to [take on the larger effort necessary](https://www.youtube.com/watch?v=AbSehcT19u0) to perform a proper fix for a problem rather than just applying a band-aid.

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Workarounds-for-common-issues.md: [**before**](https://github.com/flutter/flutter/blob/14df7be3f9471a97f34e4601fb7710850373ac3b/docs/wiki_archive/Workarounds-for-common-issues.md) / [**after**](https://github.com/flutter/flutter/blob/c8d84a71b709520d52c7dac24a91247831317057/docs/wiki_archive/Workarounds-for-common-issues.md)