Remove use of deprecated Domain API (#3762)

Use of this feature [has been discouraged for a long time](https://nodejs.org/api/domain.html).

Since most of our code is now bubbling through async, we aren't really getting these "vendor errors" anymore.

Errors that _do_ bubble up through the services have been reported to Sentry since #3706, though they seem to be missing a bunch of their stack traces. Sentry also seems to be combining unrelated internal errors. (https://github.com/badges/shields/issues/3709#issuecomment-514299441) Maybe this will help.

core/base-service/legacy-request-handler.js

@@ -1,11 +1,8 @@
 'use strict'
 
-// eslint-disable-next-line node/no-deprecated-api
-const domain = require('domain')
 const request = require('request')
 const queryString = require('query-string')
 const makeBadge = require('../../gh-badges/lib/make-badge')
-const log = require('../server/log')
 const { setCacheHeaders } = require('./cache-headers')
 const {
   Inaccessible,
@@ -32,12 +29,6 @@ const freqRatioMax = 1 - minAccuracy
 // Request cache size of 5MB (~5000 bytes/image).
 const requestCache = new LruCache(1000)
 
-// Deep error handling for vendor hooks.
-const vendorDomain = domain.create()
-vendorDomain.on('error', err => {
-  log.error('Vendor hook error:', err.stack)
-})
-
 // These query parameters are available to any badge. They are handled by
 // `coalesceBadge`.
 const globalQueryParams = new Set([
@@ -254,51 +245,47 @@ function handleRequest(cacheHeaderConfig, handlerOptions) {
     // to pass a callback.
     cachingRequest.asPromise = promisify(cachingRequest)
 
-    vendorDomain.run(() => {
-      const result = handlerOptions.handler(
-        filteredQueryParams,
-        match,
-        // eslint-disable-next-line mocha/prefer-arrow-callback
-        function sendBadge(format, badgeData) {
-          if (serverUnresponsive) {
-            return
-          }
-          clearTimeout(serverResponsive)
-          // Check for a change in the data.
-          let dataHasChanged = false
-          if (
-            cached !== undefined &&
-            cached.data.badgeData.text[1] !== badgeData.text[1]
-          ) {
-            dataHasChanged = true
-          }
-          // Add format to badge data.
-          badgeData.format = format
-          // Update information in the cache.
-          const updatedCache = {
-            reqs: cached ? cached.reqs + 1 : 1,
-            dataChange: cached
-              ? cached.dataChange + (dataHasChanged ? 1 : 0)
-              : 1,
-            time: +reqTime,
-            interval: cacheInterval,
-            data: { format, badgeData },
-          }
-          requestCache.set(cacheIndex, updatedCache)
-          if (!cachedVersionSent) {
-            const svg = makeBadge(badgeData)
-            setCacheHeadersOnResponse(ask.res, badgeData.cacheLengthSeconds)
-            makeSend(format, ask.res, end)(svg)
-          }
-        },
-        cachingRequest
-      )
-      if (result && result.catch) {
-        result.catch(err => {
-          throw err
-        })
-      }
-    })
+    const result = handlerOptions.handler(
+      filteredQueryParams,
+      match,
+      // eslint-disable-next-line mocha/prefer-arrow-callback
+      function sendBadge(format, badgeData) {
+        if (serverUnresponsive) {
+          return
+        }
+        clearTimeout(serverResponsive)
+        // Check for a change in the data.
+        let dataHasChanged = false
+        if (
+          cached !== undefined &&
+          cached.data.badgeData.text[1] !== badgeData.text[1]
+        ) {
+          dataHasChanged = true
+        }
+        // Add format to badge data.
+        badgeData.format = format
+        // Update information in the cache.
+        const updatedCache = {
+          reqs: cached ? cached.reqs + 1 : 1,
+          dataChange: cached ? cached.dataChange + (dataHasChanged ? 1 : 0) : 1,
+          time: +reqTime,
+          interval: cacheInterval,
+          data: { format, badgeData },
+        }
+        requestCache.set(cacheIndex, updatedCache)
+        if (!cachedVersionSent) {
+          const svg = makeBadge(badgeData)
+          setCacheHeadersOnResponse(ask.res, badgeData.cacheLengthSeconds)
+          makeSend(format, ask.res, end)(svg)
+        }
+      },
+      cachingRequest
+    )
+    if (result && result.catch) {
+      result.catch(err => {
+        throw err
+      })
+    }
   }
 }