tests/cmsis_rtos_v1: relax timing check a bit

Commit  33c64c25 ("tests/cmsis_rtos_v1: Correct timing assumptions")
introduced a stricter criteria where time spent has to match the clock
within 1% discrepancy. It is zassert_true(diff < max && diff > min)
meaning _less than_ 1%.

The test uses a 1-second delay. When SYS_CLOCK_TICKS_PER_SEC=100 that
means a single tick discrepancy would overflow the test.

Let's be inclusive and allow up to 1% instead. That allows for this
test to pass on m2gl025_miv when using 100 ticks per sec.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>