Simplify ci-conda-yml workflow file

[user202729]

• use the trick to allow simple listing of configurations that are included in pull request. (specifically it works as follows: in a pull_request, is-pull-request variable is true, thus exclude: {is-pull-request: true} will delete all the normal ones, then include: is processed. In a branch (not pull request), the exclude does nothing, and the include also does nothing since there are already these options. )
• change success() || failure() to !cancelled() to avoid confusion.

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edit: supposedly the conda CI workflow is going away "very soon" though (#39176 (comment)). May be not worth it.

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