Add check for empty CertifyBad nodes in query bad

[robert-cronin]

Description of the PR

Fixes #2362

PR Checklist

• All commits have a Developer Certificate of Origin (DCO) -- they are generated using -s flag to git commit.
• All new changes are covered by tests
• If GraphQL schema is changed, make generate has been run
• If GraphQL schema is changed, GraphQL client updates/additions have been made
• If OpenAPI spec is changed, make generate has been run
• If ent schema is changed, make generate has been run
• If collectsub protobuf has been changed, make proto has been run
• All CI checks are passing (tests and formatting)
• All dependent PRs have already been merged

[robert-cronin]

Some manual testing

With nodes, same behaviour as before:

❯ go run ./cmd/guacone/main.go query bad
{"level":"info","ts":1733969713.5684905,"caller":"logging/logger.go:79","msg":"Logging at info level","guac-version":"v0.0.1-custom"}
{"level":"info","ts":1733969713.5685332,"caller":"cli/init.go:65","msg":"Using config file: /home/rob/go/src/guacsec/guac/guac.yaml","guac-version":"v0.0.1-custom"}
✔ pkg:maven/org.apache.logging.log4j/log4j-core@2.8.1 (testing)
Visualizer url: http://localhost:3000/?path=23279,7283,7282,3893,63,10983,303,302,301,1

No nodes:

❯ go run ./cmd/guacone/main.go query bad
{"level":"info","ts":1733969516.913059,"caller":"logging/logger.go:79","msg":"Logging at info level","guac-version":"v0.0.1-custom"}
{"level":"info","ts":1733969516.9131167,"caller":"cli/init.go:65","msg":"Using config file: /home/rob/go/src/guacsec/guac/guac.yaml","guac-version":"v0.0.1-custom"}
No CertifyBad nodes found!

[pxp928]

Thank you!