lts-release-mail: Handle commits with multiple Change-Id lines

Some commits (dependabot specifically) appear to have 2 Change-Id
lines in the commit description, and one which belongs to the TF
Gerrit is actually the last one. So, rework Change-Id parsing to
handle such cases.

Addresses https://linaro.atlassian.net/browse/TFC-692

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Ia6bb60e2490ac72ac0aeead3bc8571d14f8a00da
1 file changed