build: move system and samples test from Node 10 to Node 12 (#195)

This PR was generated using Autosynth. 🌈

Synth log will be available here:
https://source.cloud.google.com/results/invocations/ba2d388f-b3b2-4ad7-a163-0c6b4d86894f/targets

- [ ] To automatically regenerate this PR, check this box.

Source-Link: googleapis/synthtool@05de3e1

synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/teeny-request.git",
-        "sha": "e092cabc079e57174599cd63ca7644433f0e3685"
+        "sha": "9aa097e207f2f761b2410358b3f263f5a4d30139"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "1a60ff2a3975c2f5054431588bd95db9c3b862ba"
+        "sha": "05de3e1e14a0b07eab8b474e669164dbd31f81fb"
       }
     }
   ],
@@ -30,19 +30,19 @@
     ".kokoro/common.cfg",
     ".kokoro/continuous/node10/common.cfg",
     ".kokoro/continuous/node10/docs.cfg",
-    ".kokoro/continuous/node10/lint.cfg",
-    ".kokoro/continuous/node10/samples-test.cfg",
-    ".kokoro/continuous/node10/system-test.cfg",
     ".kokoro/continuous/node10/test.cfg",
     ".kokoro/continuous/node12/common.cfg",
+    ".kokoro/continuous/node12/lint.cfg",
+    ".kokoro/continuous/node12/samples-test.cfg",
+    ".kokoro/continuous/node12/system-test.cfg",
     ".kokoro/continuous/node12/test.cfg",
     ".kokoro/docs.sh",
     ".kokoro/lint.sh",
     ".kokoro/populate-secrets.sh",
     ".kokoro/presubmit/node10/common.cfg",
-    ".kokoro/presubmit/node10/samples-test.cfg",
-    ".kokoro/presubmit/node10/system-test.cfg",
     ".kokoro/presubmit/node12/common.cfg",
+    ".kokoro/presubmit/node12/samples-test.cfg",
+    ".kokoro/presubmit/node12/system-test.cfg",
     ".kokoro/presubmit/node12/test.cfg",
     ".kokoro/publish.sh",
     ".kokoro/release/docs-devsite.cfg",
@@ -63,7 +63,6 @@
     "CONTRIBUTING.md",
     "LICENSE",
     "api-extractor.json",
-    "package-lock.json.1831917975",
     "renovate.json"
   ]
 }