docs: refine packages and container-registry command help text

What does this MR do?

Documentation review pass for the new glab packages and glab container-registry command groups, tracked in #8367 (closed). Since these doc pages are auto-generated from the command source, the fixes are made in the Short/Long/flag strings and the pages regenerated with make gen-docs.

Changes, all aligned with the glab documentation style guide:

• Synopsis no longer restates the Short description (style guide: "avoid repeating information from the short description"). Affects packages list/upload/delete and container-registry repository delete/list/view and tag list/view.
• packages list --package-type flag label rendered as a run-on sentence (Package type composer, conan, debian…). Now reads Filter packages by type. One of: composer, conan, …, terraform_module.
• packages delete --yes dropped the manual (default false) (the guide says not to annotate false-default booleans; the container-registry delete commands already omit it).
• packages group Synopsis dropped the time-relative "currently".

Verification

• make build, make gen-docs (no stale diff)
• go test ./internal/commands/packages/... ./internal/commands/container_registry/... — all pass
• Vale: 0 errors; all server-side pre-push hooks (vale, build, check-generated, go-test, go-lint) pass

Related issues

Related to #8367 (closed)