scripts/yocto_testresults_query.py: fix regression reports for branches with slashes

scripts/yocto_testresults_query.py: fix regression reports for branches with slashes

Regression reports are not generated on some integration branches because
yocto_testresults_query.py truncates branches names with slashes when it passes
it to resulttool. For example, "abelloni/master-next" is truncated to "abelloni"

Fix this unwanted branch truncation by fix tag parsing in yocto-testresults

Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>