ci: fix Coverity false positives/negatives

The regular expression used to enumerate the files that have been
analysed by Coverity is fairly fallible, and sometimes catches more or
less than intended.

This change instead looks for an alternative line which is easier to
parse, which gives us the correct list of analysed files.

Signed-off-by: Chris Kay <chris.kay@arm.com>
Change-Id: Iac6933ac45e9e1e3d01c6049e3c97c770367de55
1 file changed