Deprecate JUnit 4 support in the TestContext framework

Closes gh-34794

Author: sbrannen

framework-docs/modules/ROOT/pages/testing/annotations/integration-junit4.adoc

@@ -1,6 +1,13 @@
 [[integration-testing-annotations-junit4]]
 = Spring JUnit 4 Testing Annotations
 
+[WARNING]
+====
+JUnit 4 support is deprecated since Spring Framework 7.0 in favor of the
+xref:testing/testcontext-framework/support-classes.adoc#testcontext-junit-jupiter-extension[`SpringExtension`]
+and JUnit Jupiter.
+====
+
 The following annotations are supported only when used in conjunction with the
 xref:testing/testcontext-framework/support-classes.adoc#testcontext-junit4-runner[SpringRunner],
 xref:testing/testcontext-framework/support-classes.adoc#testcontext-junit4-rules[Spring's JUnit 4 rules], or
@@ -206,6 +213,3 @@ Kotlin::
 ----
 <1> Repeat this test ten times.
 ======
-
-
-

framework-docs/modules/ROOT/pages/testing/testcontext-framework/support-classes.adoc

@@ -483,6 +483,13 @@ Kotlin::
 [[testcontext-junit4-runner]]
 === Spring JUnit 4 Runner
 
+[WARNING]
+====
+JUnit 4 support is deprecated since Spring Framework 7.0 in favor of the
+xref:testing/testcontext-framework/support-classes.adoc#testcontext-junit-jupiter-extension[`SpringExtension`]
+and JUnit Jupiter.
+====
+
 The Spring TestContext Framework offers full integration with JUnit 4 through a custom
 runner (supported on JUnit 4.12 or higher). By annotating test classes with
 `@RunWith(SpringJUnit4ClassRunner.class)` or the shorter `@RunWith(SpringRunner.class)`
@@ -538,6 +545,13 @@ be configured through `@ContextConfiguration`.
 [[testcontext-junit4-rules]]
 === Spring JUnit 4 Rules
 
+[WARNING]
+====
+JUnit 4 support is deprecated since Spring Framework 7.0 in favor of the
+xref:testing/testcontext-framework/support-classes.adoc#testcontext-junit-jupiter-extension[`SpringExtension`]
+and JUnit Jupiter.
+====
+
 The `org.springframework.test.context.junit4.rules` package provides the following JUnit
 4 rules (supported on JUnit 4.12 or higher):
 
@@ -607,6 +621,13 @@ Kotlin::
 [[testcontext-support-classes-junit4]]
 === JUnit 4 Base Classes
 
+[WARNING]
+====
+JUnit 4 support is deprecated since Spring Framework 7.0 in favor of the
+xref:testing/testcontext-framework/support-classes.adoc#testcontext-junit-jupiter-extension[`SpringExtension`]
+for JUnit Jupiter.
+====
+
 The `org.springframework.test.context.junit4` package provides the following support
 classes for JUnit 4-based test cases (supported on JUnit 4.12 or higher):