[chore][extension/healthcheckv2] Move package test to generated (open…

…-telemetry#32725)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
`goleak` checks are enabled by the health check v2 extension, but
they're in `package_test.go` instead of `generated_package_test.go`.
This PR is the result of running `make generate` locally, as it creates
the `generated_package_test.go`, which ends up conflicting with the
`package_test.go` file.