openqa-bootstrap: Refresh and retry in case of package changes

[kalikiana]

Packages may be deleted before they can be installed.

See: https://progress.opensuse.org/issues/165024

[okurz]

From CI checks:

+ make test-checkstyle
shellcheck -x $(file --mime-type script/* t/* container/worker/*.sh tools/* | sed -n 's/^\(.*\):.*text\/x-shellscript.*$/\1/p')

In script/openqa-bootstrap line 98:
packages="${pkgs[@]}"
         ^----------^ SC2124 (warning): Assigning an array to a string! Assign as array, or use * instead of @ to concatenate.

For more information:
  https://www.shellcheck.net/wiki/SC2124 -- Assigning an array to a string! A...
make: *** [Makefile:302: test-shellcheck] Error 1

[okurz]

Another failed style check but trivial to fix