Changes

scripts/{manuals,tarballs}: skip old sigtran tags

After the old libosmo-sccp.git tags have been imported into
libosmo-sigtran.git, they now need to be ignored in the manuals and
release tarballs job.

Related: OS#6683
Change-Id: Ia182f79ba3f0a80b98af3c1c77a1390f5d08ca93

ansible/hosts: add comments with usage hints

When adding build5, these steps were not intuitive so add some
documentation hints about them.

Change-Id: I7b9c14db47d747dab4d96464ab67f4bec5cf9b7a

scripts/repo-install-test: add disconnect hint

Add a hint that would have been useful when we set up build5.

Change-Id: I208cacaaf4018dc3adf5c4b878147c19769381ff

jobs/master,gerrit: use io_uring seccomp profile

Use the seccomp profile not only in ttcn3 testsuites, but also in
master-builds and gerrit-verifications so we can test io_uring there
too.

CI happened to work without this for libosmocore on build4 because of a
specific docker version where io_uring was not yet (fully?) disabled in
the default seccomp profile. It did not work without this patch on
build5 where we currently have a newer docker version.

Related: OS#6405, OS#6186
Related: docker-playground I27567c2a5d9543c3509c316226c082ab950c5ebc
Change-Id: I71df7f7eeb79b831fb67d2cda377cf1d0619b93d