[ci] Switch podspec check over to ARM (flutter#6791)

Completes the switch of podspec checks to ARM, following up from flutter/packages#6782
- Brings the new target out of bringup mode.
- Removes the old target.
- Fixes the build ID of the swift-format CIPD package, since the previous one was copied from the other target, but the arm64 version of the package has a different build ID.

Fixes flutter#141493

.ci.yaml

@@ -961,30 +961,15 @@ targets:
  }
 
  ### iOS+macOS tasks ###
- # TODO(stuartmorgan): Move this to ARM once google_maps_flutter has ARM
- # support. `pod lint` makes a synthetic target that doesn't respect the
- # pod's arch exclusions, so fails to build.
- - name: Mac_x64 check_podspecs
- recipe: packages/packages
- timeout: 30
- properties:
- version_file: flutter_master.version
- target_file: macos_repo_checks.yaml
- dependencies: >
- [
- {"dependency": "swift_format", "version": "build_id:8797338980206841409"}
- ]
-
  - name: Mac_arm64 macos_repo_checks
  recipe: packages/packages
- bringup: true # New target
  timeout: 30
  properties:
  version_file: flutter_master.version
  target_file: macos_repo_checks.yaml
  dependencies: >
  [
- {"dependency": "swift_format", "version": "build_id:8797338980206841409"}
+ {"dependency": "swift_format", "version": "build_id:8797338979890974865"}
  ]
 
  ### macOS desktop tasks ###