fix(cluster): critical reliability and templating fixes

[philippemnoel]

I caught these while working on the @paradedb fork. Figured these changes would benefit upstream and reduce our diff:

• Fix endpointCA in barman object store template: use coalesce/default so it falls back to the generated CA bundle name and default key when only .endpointCA.create is set without explicit .name/.key
• Fix databases.yaml templating:
  • Default database owner to the database name when .owner is not specified
  • Use hasKey instead of with for isTemplate, allowConnections, and connectionLimit so that false/0 values are correctly rendered instead of silently skipped
  • Default schema owner to the database owner when not explicitly set

(The originally proposed PID comparison fix in the logical replication stopped alerts was superseded by #868, which landed an equivalent == 0 fix while this PR was open.)

Enjoy!