Tast: GRPC panic on v6.6 stable-rc

[musamaanjum]

Full logs: https://lava.collabora.dev/scheduler/job/17061959#L22369 and https://lava.collabora.dev/scheduler/job/17089336#L5387

2024-12-27T09:34:47.499357Z GRPC error stack trace: cros
	at go.chromium.org/tast/core/internal/runner.(*testServer).forEachBundle (service.go:369)
	at go.chromium.org/tast/core/internal/runner.(*testServer).ListEntities (service.go:252)
	at go.chromium.org/tast/core/internal/protocol._TestService_ListEntities_Handler.func1 (testing.pb.go:5557)
	at go.chromium.org/tast/core/internal/rpc.serverOpts.func2 (server.go:305)
	at go.chromium.org/tast/core/internal/protocol._TestService_ListEntities_Handler (testing.pb.go:5559)
	at google.golang.org/grpc.(*Server).processUnaryRPC (server.go:1282)
	at google.golang.org/grpc.(*Server).handleStream (server.go:1616)
	at google.golang.org/grpc.(*Server).serveStreams.func1.2 (server.go:921)
	...