chore: compute latest ubi8 tag and use that instead of hardcoding '8.8' in three places and forgetting to update that when a new RHEL8.y version drops (currently 8.9-1029)

[nickboldt]

What does this PR do?

chore: compute latest ubi8 tag and use that instead of hardcoding '8.8' in three places and forgetting to update that when a new RHEL8.y version drops (currently 8.9-1029)

Signed-off-by: RHDH Build (rhdh-bot) [email protected]

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What issues does this PR fix or reference?

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How to test this PR?

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PR Checklist

As the author of this Pull Request I made sure that:

• [x] The Eclipse Contributor Agreement is valid
• [x] Code produced is complete
• [x] Code builds without errors
• [ ] Tests are covering the bugfix
• [x] The repository devfile is up to date and works, if one exists
• [x] Sections What issues does this PR fix or reference and How to test this PR completed
• [x] Relevant user documentation updated
• [x] Relevant contributing documentation updated
• [x] CI/CD changes implemented, documented and communicated

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