Add DEV/INT repository signing certificate to Process Signature job (#468)

Part of https://github.com/NuGet/Engineering/issues/1402

Author: loic-sharma

src/Validation.PackageSigning.ProcessSignature/Settings/dev.json

@@ -19,7 +19,7 @@
   },
   "ProcessSignature": {
     "AllowedRepositorySigningCertificates": [
-      "0e5f38f57dc1bcc806d8494f4f90fbcedd988b46760709cbeec6f4219aa6157d"
+      "cf6ce6768ef858a3a667be1af8aa524d386c7f59a34542713f5dfb0d79acf3dd"
     ],
     "V3ServiceIndexUrl": "https://apidev.nugettest.org/v3/index.json"
   },

src/Validation.PackageSigning.ProcessSignature/Settings/int.json

@@ -18,7 +18,9 @@
     "ConnectionString": "DefaultEndpointsProtocol=https;AccountName=nugetint0;AccountKey=$$Int-NuGetInt0Storage-Key$$"
   },
   "ProcessSignature": {
-    "AllowedRepositorySigningCertificates": [],
+    "AllowedRepositorySigningCertificates": [
+      "cf6ce6768ef858a3a667be1af8aa524d386c7f59a34542713f5dfb0d79acf3dd"
+    ],
     "V3ServiceIndexUrl": "https://apiint.nugettest.org/v3/index.json"
   },