feat(proxy): test proxy connection with an authenticated route

[Neki]

About the changes

Update test-connection.yaml in the Unleash proxy Helm chart to use an authenticated route.

The currently used route /proxy/health does not require authentication. The Authentication header is ignored for this route. Even if there's an issue with the way client shared secrets are configured, the test-connection.yaml test will succeed.

Using the /proxy route (which does require authentication) allows testing a shared secret.

This change implements the recommended method to test the proxy deployment from https://docs.getunleash.io/how-to/how-to-run-the-unleash-proxy#verify-that-the-proxy-is-working

Also update the way wget is called (the Authentication header was not correctly set, but as it was ignored this mistake was not visible).

Note: The same Helm value is used to configure the proxy shared secrets environment variable, and the authentication header in test-connection.yaml. As such, as long as the chart is correct, the user can't actually make a mistake here.

However, this test is misleading to a user reading the chart templates and manually reproducing the test against the deployed proxy, as the current test does not actually validates shared secrets.

Important files

This change should be easy to review (it's a three line change).

I manually tested the Helm chart with this change against our environment, and checked that helm test still works.

Discussion points

N/A

[Neki]

Thanks for the review, I bumped the chart version.