fix(ci): remove partial semver docker tags

[deanq]

Summary

• Remove partial semver Docker tags (:1, :1.1) from all four image builds (GPU, CPU, LB, LB-CPU)
• Keeps only full version tags (:1.1.1) and :latest for default branch
• Partial tags cause overwrites across minor/patch releases, making rollbacks unreliable

Test plan

• CI workflow syntax validates (GitHub Actions linter)
• Next release produces only :<version> and :latest tags
• No :major or :major.minor tags appear on Docker Hub