Improve Lock contention dashboard naming and UX + "Database: All" option

• Rename dashboard: '13. Lock blocks details' → '13. Lock contention'
• Update UID: 'lock-waits-details' → 'lock-contention'
• Clean up panel titles: remove redundant 'lock blocks' phrasing
  • 'Lock blocks overview' → 'Blocking overview'
  • 'Lock blocks count' → 'Lock conflicts'
  • 'Lock block duration' → 'Wait duration'
  • 'Lock blocks by lock type' → 'By lock type'
  • 'Blocker transaction duration' → 'Blocker age'
  • 'Lock blocks by table' → 'By table'
  • 'Lock blocks details' → 'Blocking tree'
• Update legends to match panel titles
• Simplify panel descriptions
• Reorder table columns: blocked_pid → blocker_pid → blocked_ms
• Add 'All' option for database filter with proper regex matching