Remove Spring Security OAuth Auto-Configuration

This commit removes auto-configuration support for Spring Security
OAuth, paving the way for the introduction of auto-configuration for
Spring Security 5's new OAuth-related features.

Closes gh-10255

spring-boot-docs/pom.xml

@@ -772,11 +772,6 @@
 			<artifactId>spring-security-web</artifactId>
 			<optional>true</optional>
 		</dependency>
-		<dependency>
-			<groupId>org.springframework.security.oauth</groupId>
-			<artifactId>spring-security-oauth2</artifactId>
-			<optional>true</optional>
-		</dependency>
 		<dependency>
 			<groupId>org.springframework.social</groupId>
 			<artifactId>spring-social-config</artifactId>