codecov_helper.py: Use current checkout's path to trace2covjson.json

The code referred to a repo checkout in $SHARE_FOLDER. For some reason,
that checkout was removed, breaking code coverage builds.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I972e1f67b7ee316871e0dbfa5c1d6d2c5de9ba75
1 file changed