Fix GRPCRoute definition based on experimental evidence

[evankanderson]

Summary

With the previous definition, either as:

rules:
- matches: []

or

rules:
- backendRefs: ...
  # no matches

I would get an error:

Details: unexpected HTTP status code received from server: 404 (Not Found); transport: received unexpected content-type "application/json"

This configuration seems to successfully route traffic (proven with the following config):

grpc_server:
  host: api.custcodian.dev
  port: 443
  insecure: false
identity:
  cli:
    issuer_url: https://auth.custcodian.dev
    client_id: minder-cli
    realm: login

Change Type

Mark the type of change your PR introduces:

• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

Manual testing on custcodian.dev domain.

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[coveralls]

coverage: 57.272%. remained the same
when pulling 6f312cb on evankanderson:http-routes-fix
into a8d2baa on mindersec:main.