docker: Add centos7 to dockerstatic dockerfiles

[Haroon-Khel]

• commit message has one of the standard prefixes
• faq.md updated if appropriate
• other documentation is changed or added (if applicable)
• playbook changes run through VPC or QPC (if you have access)
• VPC/QPC not applicable for this PR
• for inventory.yml changes, bastillion/nagios/jenkins updated accordingly

Security support for centos7 ends in June of this year, so its worth having a few containers on our machines until then
https://endoflife.date/centos

[sxa]

I didn't realise we didn't already have one of these so yeah if it is suitable for passing the tests I'm ok with adding it for a few months :-)

[Haroon-Khel]

Created https://ci.adoptium.net/computer/test-docker-centos7-x64-1/

[Haroon-Khel]

Its git version is quite old

[root@664a8be7aebb ~]# git --version
git version 1.8.3.1

Causing problems with tests https://ci.adoptium.net/job/Test_openjdk17_hs_sanity.functional_x86-64_linux/405/console

12:28:26  get functional test material...
12:28:26  git clone --depth 1 --reference-if-able /home/jenkins/openjdk_cache -b master https://github.com/eclipse-openj9/openj9.git
12:28:26  error: unknown option `reference-if-able'
12:28:26  usage: git clone [options] [--] <repo> [<dir>]
12:28:26  
12:28:26      -v, --verbose         be more verbose
12:28:26      -q, --quiet           be more quiet
12:28:26      --progress            force progress reporting

Failing tests