Use StartActivityForResult to launch the intent.

Revert back to StartActivity once HelpUtils.getHelpIntent is
refactored.
More info in b/38230998

Bug: 36604276
Bug: 33090449
Test: Tapping on Analog accessory notification launch
the support article in GMH app.
Change-Id: If30f7bc627b0a9cf90ceb875665b575e7f69b16d