Replace otapi3 workflows with legacy variants

No need for otapi3 branch workflows here

.github/workflows/ci-otapi3-legacy.yml

@@ -1,4 +1,4 @@
-name: CI(OTAPI3)
+name: CI(OTAPI3) Legacy
 
 on: [push]
 

.github/workflows/ci-otapi3-nuget.yml

@@ -1,30 +0,0 @@
-name: Deploy NuGet(OTAPI3)
-
-on:
-  push:
-    branches: [ nuget-release ]
-  pull_request:
-    branches: [ nuget-release ]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-    environment: release
-
-    steps:
-    - uses: actions/checkout@v3
-    - name: Setup .NET
-      uses: actions/setup-dotnet@v2
-      with:
-        dotnet-version: 6.0.400
-    - name: Restore dependencies
-      run: dotnet restore
-    - name: Build
-      run: dotnet build TShock.sln --configuration Release --no-restore
-    - name: Test
-      run: dotnet test --no-build --verbosity normal --configuration Release
-
-    # Publish
-    - name: Push TShockAPI
-      run: dotnet nuget push TShockAPI/bin/Release/*.nupkg -k ${{ secrets.NUGET_API_KEY }} -s https://api.nuget.org/v3/index.json