gpuwork: Fix GPU time threshold overflow due to bad literals

The overflow leads to threshold being too low, which generates
insgnificant data. Set this to 10s.

Flag: EXEMPT bugfix
Bug: 347657694
Test: statsd_testdrive 10147
Change-Id: Ibb21baaf825ec148a0a0bc01f0416586214886db
Signed-off-by: Varad Gautam <varadgautam@google.com>