Use docker to look up current context vs hardcoding to "default"

[rayterrill]

What does this change

Use docker to look up current context vs hardcoding to "default"

For example if it introduces a new command or modifies a commands output, give an example of you running the command and showing real output here.

What issue does it fix

Closes #2901

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Notes for the reviewer

Put any questions or notes for the reviewer here.

Checklist

• Did you write tests?
• Did you write documentation?
• Did you change porter.yaml or a storage document record? Update the corresponding schema file.
• If this is your first pull request, please add your name to the bottom of our Contributors list. Thank you for making Porter better! 🙇‍♀️

Reviewer Checklist

• Comment with /azp run test-porter-release if a magefile or build script was modified
• Comment with /azp run porter-integration if it's a non-trivial PR

[schristoff]

Hey!

Thank you so much for this - if you could please sign the DCO we should be able to get this merged :)

[rayterrill]

@schristoff done!

[schristoff]

/azp run porter-integration

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