Remove hack in `synth.py`

We currently have this hack in synth.py:

s.replace("src/v1/subscriber_client.js",
          "  }\n\s*/\*\*\n\s+\* The DNS address for this API service.",
          "\n    // note: editing generated code\n"
          "    this.waitForReady = function(deadline, callback) {\n"
          "      return subscriberStub.then(\n"
          "        stub => stub.waitForReady(deadline, callback),\n"
          "        callback\n"
          "      );\n"
          "    };\n"
          "    this.getSubscriberStub = function() {\n"
          "      return subscriberStub;\n"
          "    };\n"
          "\g<0>")

The code that’s getting swapped in is creating lint issues in #641. It looks like there is an issue here in the gapic generator causing the pain: https://github.com/googleapis/gapic-generator/issues/2127

[sduskis]

@JustinBeckwith, any objection to recategorize this as a “type: cleanup”, since this doesn’t affect users?

[alexander-fenster]

Sure! (I actually thought it is closed 😃 )