Proj0600: Avoid generating packages on build if not packable

The <GeneratePackageOnBuild> option has no effect when the <IsPackable> node is disabled. Removing the <GeneratePackageOnBuild> node will reduce noise.

Non-compliant

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <IsPackable>false</IsPackable>
    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
  </PropertyGroup>

</Project>

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <IsPackable>false</IsPackable>
    <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
  </PropertyGroup>

</Project>

Compliant

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <IsPackable>true</IsPackable>
    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
  </PropertyGroup>

</Project>

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <IsPackable>true</IsPackable>
    <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
  </PropertyGroup>

</Project>

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
  </PropertyGroup>

</Project>

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
  </PropertyGroup>

</Project>

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
  </PropertyGroup>

</Project>