adb-remount-test: Print log timestamp & auto-detect color

* Change --print-time to default true, and print timestamp of each log
  message.
* Auto-detect color support. If stdout if terminal, then color default
  to true, else default to false.

Bug: 243116800
Test: adb-remount-test
Change-Id: Id8425488c4b18fe0bc4dd7e50c3e2ae2e8c74cfe