The GTID state (GTID_EXECUTED and GTID_PURGED) can be reset using
RESET MASTER.

RESET MASTER only works when the binary log is enabled. If the binary
log is disabled, RESET MASTER fails with an error. This did not limit
the GTID feature in 5.6, since GTIDs could only be enabled when the
binary log was enabled.

However, since WL#6559 was pushed to 5.7.5, GTIDs can be enabled even
when the binary log is disabled. So in this case there is no way to
reset the GTID state.

Fix: Make RESET MASTER reset gtid_executed and gtid_purged even when
binary logging is disabled.

@sql/rpl_master.cc
- Fix the server bug.

@mysql-test/suite/binlog/t/binlog_anonymous_ownership.test
- Fix unrelated test race (test failed by coincidence when testing
  this bug). The test disconnected a session that was in the middle of
  an anonymous transaction and then immediately asserted that the
  counter of anonymous transactions has decremented. However, the
  counter is decremented in thread cleanup code that runs
  asynchronously, so it might not have executed at the time the
  condition was checked.  Added a synchronization step where the test
  waits for the thread to disappear.

@mysql-test/suite/sys_vars/t/gtid_purged_basic.test
- Test that RESET MASTER works even when binary log is disabled.

@mysql-test/include/rpl_init.inc
- Make tests call RESET MASTER even if binary log is disabled.

@mysql-test/suite/rpl/t/rpl_binlog_errors.test
@mysql-test/t/disabled_replication.test
- RESET MASTER no longer generates an error when binlog is disabled.

Most other test files:
- Many tests don't need to force a server restart now that
  rpl_init.inc executes RESET MASTER even on a binlog-less slave.
  (Removed force-restart from some unrelated cases too, where that
  was easy.)

@mysql-test/suite/rpl/t/rpl_simulate_create_trunk_failure.test
@sql/rpl_gtid_set.cc
- Don't force restart. Also corrected typo trunk->chunk.