docs build failed in `google-cloud-edgecontainer`

[parthea]

See https://github.com/googleapis/googleapis/blob/5ce591f2593cf3a2c5c370c0a0d761c2d889c6b1/google/cloud/edgecontainer/v1/resources.proto#L219-L223 where there is an asterisk character which is not surrounded by backticks or escaped.

This caused the docs build to fail with

sphinx.errors.SphinxWarning: /home/runner/work/google-cloud-python/google-cloud-python/packages/google-cloud-edgecontainer/google/cloud/edgecontainer_v1/types/resources.py:docstring of google.cloud.edgecontainer_v1.types.resources.Cluster.MaintenanceEvent:22:Inline emphasis start-string without end-string.

Instead of

    // Output only. The operation for running the maintenance event. Specified
    // in the format projects/*/locations/*/operations/*. If the maintenance
    // event is split into multiple operations (e.g. due to maintenance
    // windows), the latest one is recorded.
    string operation = 3 [(google.api.field_behavior) = OUTPUT_ONLY];

It should be

    // Output only. The operation for running the maintenance event. Specified
    // in the format `projects/*/locations/*/operations/*`. If the maintenance
    // event is split into multiple operations (e.g. due to maintenance
    // windows), the latest one is recorded.
    string operation = 3 [(google.api.field_behavior) = OUTPUT_ONLY];

See https://github.com/googleapis/google-cloud-python/actions/runs/8383943297/job/22960516689?pr=12482

We should add a check upstream for unsupported formatting in proto comments