Sendinblue rebranded to Brevo

[shahzadhaider1]

Description:

This PR updates references from Sendinblue to Brevo, following the company's rebranding.

• Updated naming conventions to reflect the new Brevo brand.
• The existing API key detection logic remains unchanged, as Brevo API keys follow the same pattern as before.
• API key verification continues to work with the same endpoint.
• No additional changes to the verification mechanism were necessary.

Checklist:

• Tests passing (make test-community)?
• Lint passing (make lint this requires golangci-lint)?

[nabeelalam]

Looks good! Not blocking IMO, but this may be a good opportunity to add indeterminate verification results to the detector which seem to be missing.

[rosecodym]

I'm requesting changes while we discuss secret identity internally.

discussion complete

[shahzadhaider1]

Putting this PR on hold as per our internal discussion. Updating the detector type could lead to issues due to the presence of existing secrets using the old type, while newly detected secrets would use the updated type. To resolve this, we would need to run or update some migrations. However, since this change is not a high priority at the moment, we're pausing it for now.