fix(http-server): simplify test-related scripts

Remove "acceptance", "integration" and "unit" scripts from package.json,
we are not using them.

Simplify "test" script to run all test files from the "test" directory,
instead of enumerating "unit", "integration" and "acceptance". This
removes a warning printed by mocha about "unit" and "acceptance"
directories not found.

packages/http-server/package.json

@@ -6,17 +6,14 @@
     "node": ">=8"
   },
   "scripts": {
-    "acceptance": "lb-mocha \"DIST/test/acceptance/**/*.js\"",
     "build": "npm run build:dist8 && npm run build:dist10",
     "build:apidocs": "lb-apidocs",
     "build:current": "lb-tsc",
     "build:dist8": "lb-tsc es2017",
     "build:dist10": "lb-tsc es2018",
     "clean": "lb-clean loopback-http-server*.tgz dist* package api-docs",
     "pretest": "npm run build:current",
-    "integration": "lb-mocha \"DIST/test/integration/**/*.js\"",
-    "test": "lb-mocha \"DIST/test/unit/**/*.js\" \"DIST/test/integration/**/*.js\" \"DIST/test/acceptance/**/*.js\"",
-    "unit": "lb-mocha \"DIST/test/unit/**/*.js\"",
+    "test": "lb-mocha \"DIST/test/**/*.js\"",
     "verify": "npm pack && tar xf loopback-http-server*.tgz && tree package && npm run clean"
   },
   "author": "IBM",