Before this patch RUN_TESTS condition in Dockerfile.staticbuild was
ignored and always was true.

However adding of brackets solves only part of problem. If RUN_TESTS is
empty `sh -c` returns 1 and build fails.

However if we run tests we should fail build if tests are not passed.
Ternary logic was rewritten to fair if-else.

This patch fixes it and allows build tarantool statically without
running tests.

@Totktonada: Fixed .gitlab.mk to pass RUN_TESTS environment variable to
docker build arguments.

Reviewed-by: Alexander Turenko <alexander.turenko@tarantool.org>
(cherry picked from commit 8c85dbc7)

`apt-get update <...>` fails on Debian Buster on docker_bootstrap goal
(see #4331 for the similar issue).

Added a description how to change dependencies in .travis.mk.

(cherry picked from commit 45c2576d)

Added static build using Dockerfile on Centos 7 for release
commit criteria only. Added the cleanup for cmake generating
CMakeCache.txt files and CMakeFiles directories to avoid of
cmake localy created setup failing inside the docker after
the whole tarantool path was copied into it. Added testing
into the static build, running only when RUN_TESTS environment
variable set to non empty value, used in gitlab-ci job to run
the testing after the build.

Closes #3668

(cherry picked from commit f7509186)

Implemented GitLab CI testing process additionally to existing Travis
CI. The new testing process is added to run tests faster. It requires to
control a load of machines to avoid flaky fails on timeouts. GitLab CI
allows us to run testing on our machines.

Created 2 stages for testing and deploying packages.

The testing stage contains the following jobs that are run for all
branches:

* Debian 9 (Stretch): release/debug gcc.
* Debian 10 (Buster): release clang8 + lto.
* OSX 14 (Mojave): release.
* FreeBSD 12: release gcc.

And the following jobs that are run of long-term branches (release
branches: for now it is 1.10, 2.1 and master):

* OSX 13 (Sierra): release clang.
* OSX 14 (Mojave): release clang + lto.

The deployment stage contains the same jobs as we have in Travis CI.
They however just build tarballs and packages: don't push them to S3 and
packagecloud.

In order to run full testing on a short-term branch one can name it with
'-full-ci' suffix.

The additional manual work is needed when dependencies are changed in
.travis.mk file ('deps_debian' or 'deps_buster_clang_8' goals):

 | make GITLAB_USER=foo -f .gitlab.mk docker_bootstrap

This command pushes docker images into GitLab Registry and then they are
used in testing. Pre-built images speed up testing.

Fixes #4156