add sdk constraints where missing to prepare for nnbd flag flip (#68611)

diff --git a/dev/customer_testing/pubspec.yaml b/dev/customer_testing/pubspec.yaml
index 0471daa..8036429 100644
--- a/dev/customer_testing/pubspec.yaml
+++ b/dev/customer_testing/pubspec.yaml
@@ -2,7 +2,7 @@
 description: Tool to run the tests listed in the flutter/tests repository.
 
 environment:
-  sdk: any
+  sdk: '>=2.9.0 <3.0.0'
 
 dependencies:
   args: 1.6.0
diff --git a/dev/integration_tests/android_semantics_testing/pubspec.yaml b/dev/integration_tests/android_semantics_testing/pubspec.yaml
index f31ee94..77d4867 100644
--- a/dev/integration_tests/android_semantics_testing/pubspec.yaml
+++ b/dev/integration_tests/android_semantics_testing/pubspec.yaml
@@ -1,5 +1,7 @@
 name: android_semantics_testing
 description: Integration testing library for Android semantics
+environment:
+  sdk: '>=2.9.0 <3.0.0'
 
 dependencies:
   flutter:
diff --git a/dev/integration_tests/android_views/pubspec.yaml b/dev/integration_tests/android_views/pubspec.yaml
index 127ab8e..4666377 100644
--- a/dev/integration_tests/android_views/pubspec.yaml
+++ b/dev/integration_tests/android_views/pubspec.yaml
@@ -1,6 +1,8 @@
 name: platform_views
 description: An integration test for embedded platform views
 version: 1.0.0+1
+environment:
+  sdk: '>=2.9.0 <3.0.0'
 
 dependencies:
   flutter:
diff --git a/dev/integration_tests/hybrid_android_views/pubspec.yaml b/dev/integration_tests/hybrid_android_views/pubspec.yaml
index efdb489..d8ca6b4 100644
--- a/dev/integration_tests/hybrid_android_views/pubspec.yaml
+++ b/dev/integration_tests/hybrid_android_views/pubspec.yaml
@@ -1,6 +1,8 @@
 name: hybrid_platform_views
 description: An integration test for hybrid composition on Android
 version: 1.0.0+1
+environment:
+  sdk: '>=2.9.0 <3.0.0'
 
 dependencies:
   flutter:
diff --git a/dev/integration_tests/image_loading/pubspec.yaml b/dev/integration_tests/image_loading/pubspec.yaml
index 428805a..dd3111b 100644
--- a/dev/integration_tests/image_loading/pubspec.yaml
+++ b/dev/integration_tests/image_loading/pubspec.yaml
@@ -1,5 +1,7 @@
 name: image_loading
 description: Integration testing library for Android semantics
+environment:
+  sdk: '>=2.9.0 <3.0.0'
 
 dependencies:
   flutter:
diff --git a/dev/integration_tests/web_compile_tests/pubspec.yaml b/dev/integration_tests/web_compile_tests/pubspec.yaml
index f546711..b429c78 100644
--- a/dev/integration_tests/web_compile_tests/pubspec.yaml
+++ b/dev/integration_tests/web_compile_tests/pubspec.yaml
@@ -1,4 +1,6 @@
 name: web_compile_tests
+environment:
+  sdk: '>=2.9.0 <3.0.0'
 
 dependencies:
   flutter: