refactored upload file service to remove duplicate file name building code
refactored upload file service to remove duplicate file name building code

projectkudu/SiteExtensionGallery,KuduApps/NuGetGallery,grenade/NuGetGallery_download-count-patch,KuduApps/NugetGallery16Fx45-DeleteMe,KuduApps/NugetGallery21Fx45-DeleteMe,KuduApps/NugetGallery16Fx45-DeleteMe,KuduApps/NuGetGallery,grenade/NuGetGallery_download-count-patch,KuduApps/NuGetGallery,mtian/SiteExtensionGallery,JetBrains/ReSharperGallery,KuduApps/NugetGallery21Fx45-DeleteMe,mtian/SiteExtensionGallery,skbkontur/NuGetGallery,skbkontur/NuGetGallery,KuduApps/NuGetGallery,kudustress/NuGetGallery,ScottShingler/NuGetGallery,JetBrains/ReSharperGallery,ScottShingler/NuGetGallery,kudustress/NuGetGallery,grenade/NuGetGallery_download-count-patch,kudustress/NuGetGalleryOptmized,kudustress/NuGetGallery2,kudustress/NuGetGalleryOptmized,projectkudu/SiteExtensionGallery,skbkontur/NuGetGallery,projectkudu/SiteExtensionGallery,ScottShingler/NuGetGallery,kudustress/NuGetGallery2,KuduApps/NuGetGallery,JetBrains/ReSharperGallery,mtian/SiteExtensionGallery