Fix for Chromedriver not connecting to adb running on non-default port. Take 2

Fixes #3717 
Depends on appium/appium-adb#47 being merged in.
Code on line 210 is invoked conditionally, based on code in 208 `if (!alreadyRestarted)`.  If that's the only place the `adb` object is used, then we only need to instantiate the ADB object if that condition is true. In that case, you should make `adb` a local variable and instantiate it somewhere around line 209.