[fix] hadolint warnings to base and rstudio Dockerfiles

[jstourac]

These changes shouldn't have any functional impact.

This fixes the CI checks and should be cherry-picked to main.

---

But just now, when raising this. I'm thinking whether we actually want it in the rhoai-2.8 in the end... Please, let me know, guys.

[harshad16]

/lgtm
/approve

thanks 👍

[openshift-ci]

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[riprasad]

@harshad16 We are in Code freeze and lets respect the protocol. Please do not accepts any changes in the release branch that doesn't have a blocker JIRA associated with it.

Please reset the branch to point 37e8782

[harshad16]

@riprasad Thanks for pointing us in the right direction.
we have reverted to commit 37e8782 in https://github.com/red-hat-data-services/notebooks/commits/rhoai-2.8/

@jstourac , please open a separate PR for main.

[jstourac]

@harshad16 Checking the main and looks like it doesn't contain the changes from upstream yet. I'll wait till it's time to do this then. Thanks.

Update: created #179.