Bump spotbugs major version

What does this MR do and why?

This MR updates the Spotbugs SAST analyzer image to the latest major version v6 for the latest CI template

v6 was released in Add JDK21 and remove JDK11 (gitlab-org/security-products/analyzers/spotbugs!243 - merged)

However, as v6 contains a breaking change that was not approved, we will only be updating latest CI template to v6 while keeping the stable CI template as v5. Full details in this comment.

References

Update spotbugs major version in SAST templates (#517169 - closed)

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