issue_templates: Update labels for new bugs

New GL instance has Issue::Bug label instead of Bug we had before.
Updating labels and add default team maintenance for all new bugs to
improve searching

Signed-off-by: Pavel Zhukov <pavel.zhukov@huawei.com>

.gitlab/issue_templates/Bug.md

@@ -28,4 +28,4 @@
 
 (link to upstream patch, merge/pull request)
 
-/label ~bug ~needs-investigation
+/label ~Issue:Bug ~needs-investigation ~team::maintenance