[stable/joomla] Update to the recommended pvc patterns.

[AmandaCameron]

This is a split-off of PR #408 to just contain the chart joomla.
If there's any commonality in changes nessary between this PR and the others that are being submitted at once, please mention them in #408.
Some things to note:

• This initial PR will not be updating the Chart.yaml's version string, as I feel it should be done manually per-pr once each chart's otherwise acceptable.
• An automated script created the splits and the PRs, on a per-folder basis under stable, after copying the relevent files from a backup of my local copy of Update all stable PVCs to use recommended pattern. #408

[k8s-ci-robot]

Hi @AmandaCameron. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with @k8s-bot ok to test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[viglesiasce]

@k8s-bot ok to test

[k8s-ci-robot]

@AmandaCameron: The following test(s) failed:

Test name	Commit	Details	Rerun command
Jenkins Charts e2e	4771270	link	@k8s-bot e2e test this

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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