Two release plans targets same service same version.

We got two same auto PR in Go SDK for chaos. 1. https://github.com/Azure/azure-sdk-for-go/pull/27279 from https://azsdk-releaseplan-dashboard-hveph5aqhhcfhtgu.westus-01.azurewebsites.net/?releaseplan=35589 2. https://github.com/Azure/azure-sdk-for-go/pull/27254 from https://azsdk-releaseplan-dashboard-hveph5aqhhcfhtgu.westus-01.azurewebsites.net/?releaseplan=2236 My suggestion is we should not allow to create a release plan before one plan finish for one service. It will cause the generated PR out of date.