Quiet down long screenshots logcat output

With this change, a long screen shot flow generates only
the following log entries:

D Screenshot: ScrollCapture: connected to window [com.example/.ExampleActivity]
D Screenshot: onCaptureStarted
D Screenshot: end()
I Screenshot: Completed: LongScreenshot{w=1080, h=5339}

Tags covered:

LongScreenshotActivity
Screenshot
ScrollCaptureConnection
ScrollCaptureInternal
ScrollCaptureViewSupport
ScrollCaptureController
ViewRenderer

Bug: 190399332
Test: observe logcat during long screenshot
Change-Id: Ia2b018224897ad1ca153967ff9f60340a64f4815