Fix test_glob_noop_incremental

I6a98660cfe6a40bcaa978e8d7544cdffad86a7fa was submitted concurrently
with test_glob_noop_incremental and broke the test by making the
first build incremental.  Add an rm -rf out to make the test start
from a clean build.

Bug: 185591972
Test: tests/bootstrap_test.sh
Change-Id: I529aaf707b2790e5e1022ba9b2637ed7d2435bd5