Reorganize dependencies on leak_tracker. (#140233)

1. Move leak_tracker and leak_tracker_testing out of direct dependencies.
2. Move leak_tracker_flutter_testing from dev to prod dependencies for flutter_test

It is prerequisite for https://github.com/flutter/flutter/issues/135856

dev/integration_tests/gradle_deprecated_settings/pubspec.yaml

diff --git a/dev/integration_tests/gradle_deprecated_settings/pubspec.yaml b/dev/integration_tests/gradle_deprecated_settings/pubspec.yaml
index ae10cb9..c4b78d6 100644
--- a/dev/integration_tests/gradle_deprecated_settings/pubspec.yaml
+++ b/dev/integration_tests/gradle_deprecated_settings/pubspec.yaml
@@ -11,7 +11,7 @@
 
   camera_android: 0.10.8+15 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   camera_avfoundation: 0.9.13+8 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
-  camera_platform_interface: 2.6.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  camera_platform_interface: 2.7.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   camera_web: 0.3.2+3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   characters: 1.3.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   collection: 1.18.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
@@ -27,4 +27,4 @@
 flutter:
   uses-material-design: true
 
-# PUBSPEC CHECKSUM: 63c2
+# PUBSPEC CHECKSUM: 48c3