chore: remove unused system and sample test configuration from core/paginator (googleapis#8165)

Author: pearigee

core/paginator/.kokoro/presubmit/node18/samples-test.cfg

@@ -13,14 +13,12 @@
     "test": "c8 mocha build/test",
     "compile": "tsc -p .",
     "fix": "gts fix",
-    "prelint": "cd samples; npm link ../; npm install",
     "lint": "gts check",
     "prepare": "npm run compile",
     "pretest": "npm run compile",
     "docs": "jsdoc -c .jsdoc.js",
-    "presystem-test": "npm run compile",
-    "samples-test": "cd samples/ && npm link ../ && npm test && cd ../",
-    "system-test": "mocha build/system-test",
+    "samples-test": "echo 'no samples test'",
+    "system-test": "echo 'no system test'",
     "docs-test": "linkinator docs",
     "predocs-test": "npm run docs",
     "clean": "gts clean",

core/paginator/.kokoro/presubmit/node18/system-test.cfg

@@ -7,7 +7,6 @@
   },
   "include": [
     "src/*.ts",
-    "test/*.ts",
-    "system-test/*.ts"
+    "test/*.ts"
   ]
 }