Increase CLI context timeout to 20s

[eleftherias]

Summary

Users in Spain (and possibly other regions) are experience continuous context timeouts, because requests to the gRPC endpoints on the server are taking longer than 10 seconds.

This increases the timeout, under the assumption that it's better for the CLI to be slow than to error.

Change Type

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• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

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Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[coveralls]

coverage: 52.204%. remained the same
when pulling c75ae6d on eleftherias:increase-context-timeout
into 11c145f on stacklok:main.

[evankanderson]

It looks like we're creating the context with timeout around the entire runE function (in grpc.GRPCClientWrapRunE), rather than specifically around individual RPC requests. This means that interactive prompts, parsing, etc all get attributed to this timeout, rather than having a timeout specifically around reaching Minder for RPCs.