Remove nuget localization exclusion from sdk content tests

[MichaelSimons]

The Nuget localization files are excluded from the sdk content tests

https://github.com/dotnet/dotnet/blob/7a132d33c9da902b5a3c232d905bf4aaf71456fd/test/Microsoft.DotNet.SourceBuild.Tests/assets/SdkContentTests/SdkFileDiffExclusions.txt#L42

Recently Nuget localization was enabled for linux/source-only builds therefore the localization files should be validated.

[akoeplinger]

the next line about ILMerge also no longer applies, it was turned off for Nuget.Build.Task.Pack