Allow to override the sts_endpoint when using sigv4auth

[eduaquiles]

Component(s)

extension/sigv4auth

Is your feature request related to a problem? Please describe.

We have a use case where we need to override the sts_endpoint to use a private endpoint one. We couldn't find a way to do it with the current options available.

Describe the solution you'd like

The original issue that introduced the sigv4auth settings listed the sts_endpoint as an option, but it got dropped on the implementation part. Following the same approach would solve our issue.

Describe alternatives you've considered

No response

Additional context

No response

[github-actions]

Pinging code owners:

• extension/sigv4auth: @Aneurysm9 @erichsueh3

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[github-actions]

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Pinging code owners:

• extension/sigv4auth: @Aneurysm9 @erichsueh3

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[atoulme]

@Aneurysm9 @erichsueh3 please review?