feat: update gapic-generator-csharp to 1.3.16
feat: update gapic-generator-csharp to 1.3.16

Committer: da39a3ee5e6b4b0d3255bfef95601890afd80709@viacheslav-rostovtsev
PiperOrigin-RevId: 410343032

googleapis/googleapis,googleapis/googleapis