feature(connector)sdk): Adding probe to API, database and s3 example

[fivetran-sahilkhirwal]

Jira ticket

Closes https://fivetran.atlassian.net/browse/RD-1161619

Description of Change

For referencing the github example in the Concepts docs, Added probe to examples

• One for API
• One for Database ( SQL server )
• One for file connections ( AWS S3 )

Testing

• authentication/api_key

• authentication/certificates

Checklist

Some tips and links to help validate your PR:

• Tested the connector with fivetran debug command.
• Added/Updated example-specific README.md file, see the README template for the required structure and guidelines.
• Followed Python Coding Standards, refer here

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[Copilot]

Pull request overview

Adds “probe” (connectivity validation) steps to several Connector SDK examples (API key auth, SQL Server, and S3 certificate retrieval) so the examples can be referenced from Concepts docs with clearer fail-fast behavior.

Changes:

• Added S3 connectivity probing and refactored S3 certificate retrieval helper usage in the AWS certificate example.
• Added an API probe + retry/backoff logic to the API key authentication example.
• Added a SQL Server connection probe and refactored the SQL Server connector to batch-fetch rows and checkpoint periodically.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 17 comments.

Show a summary per file

File	Description
examples/common_patterns_for_connectors/authentication/certificate/retrieve_from_aws/connector.py	Adds S3 probing, refactors S3 client/cert retrieval, introduces constants/checkpoint interval.
examples/common_patterns_for_connectors/authentication/certificate/retrieve_from_aws/aws_client.py	Adds an S3Client.probe() helper for testing S3 connectivity.
examples/common_patterns_for_connectors/authentication/api_key/connector.py	Adds API probe and retry/backoff behavior for API calls; updates main debug block comments.
examples/common_patterns_for_connectors/authentication/api_key/configuration.json	Updates api_key to use angle-bracket placeholder format.
connectors/sql_server/connector.py	Adds DB probe + batching/checkpointing refactor and improves docstrings/logging.