fix: catch all requests exceptions in get_index to prevent unhandled NameResolutionError (closes #33691)

[botbikamordehai2-sketch]

What

The az find command crashes with an unhandled NameResolutionError when DNS resolution fails for the extension index endpoint (e.g., app.aladdin.microsoft.com returns NXDOMAIN). The exception is not caught by the existing except clause, causing a Python traceback instead of a user-friendly error.

Fix

Replace (requests.exceptions.ConnectionError, requests.exceptions.HTTPError, ValueError) with (requests.exceptions.RequestException, ValueError) in the get_index() function. RequestException is the base class for all exceptions raised by the requests library, including DNS resolution failures, connection errors, timeouts, and HTTP errors. This ensures any network-related error is caught and converted to a CLIError with a clear message.

Closes #33691

[azure-client-tools-bot-prd]

Hi @botbikamordehai2-sketch,
Usually we only allow pull requests to be submitted to the dev branch, please double check your pull request target branch main.

[azure-client-tools-bot-prd]

Hi @botbikamordehai2-sketch,
Since the current milestone time is less than 7 days, this pr will be reviewed in the next milestone.

[azure-pipelines]

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[yonzhan]

az find

[necusjz]

@botbikamordehai2-sketch thanks for your contribuation! however, it's covered by #33491 with a new backend service (will release in the next comming azure-cli version).