Extend artifact lifetime for release-related jobs

Artifacts of the "stress" jobs in GitLab CI are used for generating the
QA summary for a given set of releases.  It happened in the past that
these artifacts were purged before the QA summary was prepared,
unnecessarily prolonging the release process.  A complete set of
artifacts from all such jobs for a single pipeline should be less than 1
GB in size, so extend their lifetime from one day to one week as a more
reasonable compromise between availability and disk space usage.  (Note:
these jobs are also run in scheduled pipelines, but that is expected to
be acceptable in the context of artifact lifetime.)

Artifacts of the "release" jobs in GitLab CI are what we eventually
publish on the FTP server.  It happened in the past that these artifacts
were purged before we copied them to their destination, unnecessarily
prolonging the release process, even though we usually press the "Keep"
button for the "release" jobs manually to keep them around indefinitely
(as they are the source of what we publish in other places).  Since
there is only one "release" job per tag pipeline and its artifacts only
take up tens of megabytes of space, keep the artifacts of the "release"
jobs around indefinitely by default.

(cherry picked from commit 71c9d69145)

.gitlab-ci.yml

@@ -1256,7 +1256,7 @@ release:
   artifacts:
     paths:
       - "*.tar.gz"
-    expire_in: "1 day"
+    expire_in: never
 
 # Coverity Scan analysis upload
 
@@ -1420,7 +1420,7 @@ respdiff-long-third-party:
       artifacts: true
   artifacts:
     untracked: true
-    expire_in: "1 day"
+    expire_in: "1 week"
     when: always
   timeout: 2h