Fix the shell commands used to clean up after the accessibility tests.

1. The shell commands for cleaning up after the accessibility tests were
   missing some escape characters, hence not working. As a result, the device
   was left with enabled accessibility leading to subsequent CTS test failures.

2. Removed the request for a device reboot after the accessibility tests.

bug:7526252

Change-Id: I05dc735cd3ff4feb59e1513c25bb22cb1112c1e4