build(node): add KOKORO_BUILD_ARTIFACTS_SUBDIR to env (#254)

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Source-Link: googleapis/synthtool@ba9918c

Author: yoshi-automation

core/paginator/.kokoro/trampoline_v2.sh

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/nodejs-paginator.git",
-        "sha": "b5c56b5399df1310d8f95fcbebd7abe47eb4b203"
+        "sha": "f813af4685276bfe663763a7982071af5c190580"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "89c849ba5013e45e8fb688b138f33c2ec6083dc5"
+        "sha": "ba9918cd22874245b55734f57470c719b577e591"
       }
     }
   ],