fix(zone.js): remove unused Promise overwritten setter logic (#36851)

In the early Zone.js versions (< 0.10.3), `ZoneAwarePromise` did not support `Symbol.species`,
so when user used a 3rd party `Promise` such as `es6-promise`, and try to load the promise library after import of `zone.js`, the loading promise library will overwrite the patched `Promise` from `zone.js` and will break `Promise` semantics with respect to `zone.js`.

Starting with `zone.js` 0.10.3, `Symbol.species` is supported therefore this will not longer be an issue. (https://github.com//pull/34533)

Before 0.10.3, the logic in zone.js tried to handle the case in the wrong way. It did so by overriding the descriptor of `global.Promise`, to allow the 3rd party libraries to override native `Promise` instead of `ZoneAwarePromise`. This is not the correct solution, and since the `Promise.species` is now supported, the 3rd party solution of overriding `global.Promise` is no longer needed.

PR removes the wrong work around logic. (This will improve the bundle size.)

PR Close #36851

goldens/size-tracking/integration-payloads.json

@@ -3,8 +3,8 @@
     "master": {
       "uncompressed": {
         "runtime-es2015": 1485,
-        "main-es2015": 141394,
-        "polyfills-es2015": 36963
+        "main-es2015": 141151,
+        "polyfills-es2015": 36571
       }
     }
   },
@@ -22,7 +22,7 @@
       "uncompressed": {
         "runtime-es2015": 1485,
         "main-es2015": 147314,
-        "polyfills-es2015": 36963
+        "polyfills-es2015": 36571
       }
     }
   },