fix: remove unused r#type field in GooglePubSubConfig

[jetjinser]

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What's changed and what's your intention?

The option type is not used in code but needs to be provided in create sink sql and should be remove.

link #16363.

Checklist

• I have written necessary rustdoc comments
• My PR contains breaking changes. (If it deprecates some features, please create a tracking issue to remove them in the future).
• All checks passed in ./risedev check (or alias, ./risedev c)

Documentation

• My PR needs documentation updates. (Please use the Release note section below to summarize the impact on users)

Release note

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docs pr thats need to update: https://github.com/risingwavelabs/risingwave-docs/pull/2177

[tabVersion]

Previously we used the type to express the sink's behavior and now we prefer the format <format name> to express the same meaning. I think it is safe to remove. cc @xiangjinwu

[neverchanje]

For backward compatibility, I would prefer setting this field as Option<String> instead. But if there's no validation rule on this field, just removing it would be better.

BTW, pls remember to rerun ./risedev generate-with-options.

[tabVersion]

a random fault, enqueue again