tf-m-code-coverage: Make start around 19:xx UTC

To make sure that its running doesn't fall on working day per China
Standard Time, which makes it inconvinient for the team in China.

This still makes its start time different from start times of other
big jobs, though they definitely overlap in run time otherwise.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I16fda4ee99ddd62213709c00d23f0a27352bbe3a
1 file changed