build: --credential-file-override is no longer required (#377)

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Source-Link: googleapis/synthtool@94421c4

packages/google-cloud-asset/synth.metadata

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/nodejs-asset.git",
-        "sha": "6873b973cc02fd2a7a1e6015ac1d084f1ff6af7d"
+        "sha": "11629d463902df67fc0f89aaa28d67378759ab41"
       }
     },
     {
@@ -19,7 +19,7 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "5936421202fb53ed4641bcb824017dd393a3dbcc"
+        "sha": "94421c47802f56a44c320257b2b4c190dc7d6b68"
       }
     }
   ],