docs: remove spring-boot-properties-migrator from server starters

As discussed in #4022, removing the temporary properties-migrator
dependency from new server-only starter modules (server-webflux and
server-webmvc) to avoid unexpected property overrides in production
environments.

Legacy starter modules (spring-cloud-starter-gateway and
spring-cloud-starter-gateway-mvc) will retain the migrator for
backward compatibility.

Resolves #4022

Signed-off-by: Kangmin Kim <76634341+amazon7737@users.noreply.github.com>

Author: amazon7737

spring-cloud-starter-gateway-server-webflux/pom.xml

@@ -33,10 +33,5 @@
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-webflux</artifactId>
 		</dependency>
-		<!-- TODO: temporary, remove for 5.0 -->
-		<dependency>
-			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-properties-migrator</artifactId>
-		</dependency>
 	</dependencies>
 </project>

spring-cloud-starter-gateway-server-webmvc/pom.xml

@@ -33,10 +33,5 @@
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-web</artifactId>
 		</dependency>
-		<!-- TODO: temporary, remove for 5.0 -->
-		<dependency>
-			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-properties-migrator</artifactId>
-		</dependency>
 	</dependencies>
 </project>