Discontinue use of Rouge in the Reference Manual

Due to a bug in Rouge thats prevents it from working on MS Windows, we
are currently reverting back to CodeRay for source code highlighting
within the Reference Manual.

Issues: SPR-15471

src/docs/asciidoc/appendix.adoc

@@ -5,7 +5,6 @@
 :wiki-spring-framework: https://github.com/spring-projects/spring-framework/wiki
 :toc: left
 :toclevels: 2
-ifdef::backend-pdf[:source-highlighter: rouge]
 
 [[spring-whats-new]]
 == What's New in the Spring Framework

src/docs/asciidoc/core.adoc

@@ -4,7 +4,6 @@
 :api-spring-framework: {doc-root}/spring-framework/docs/{spring-version}/javadoc-api/org/springframework
 :toc: left
 :toclevels: 2
-ifdef::backend-pdf[:source-highlighter: rouge]
 
 This part of the reference documentation covers all of those technologies that are
 absolutely integral to the Spring Framework.

src/docs/asciidoc/data-access.adoc

@@ -4,7 +4,6 @@
 :api-spring-framework: {doc-root}/spring-framework/docs/{spring-version}/javadoc-api/org/springframework
 :toc: left
 :toclevels: 2
-ifdef::backend-pdf[:source-highlighter: rouge]
 
 This part of the reference documentation is concerned with data access and the
 interaction between the data access layer and the business or service layer.

src/docs/asciidoc/integration.adoc

@@ -6,7 +6,6 @@
 :doc-spring-gemfire: {doc-root}/spring-gemfire/docs/current/reference
 :toc: left
 :toclevels: 2
-ifdef::backend-pdf[:source-highlighter: rouge]
 
 This part of the reference documentation covers the Spring Framework's integration with
 a number of Java EE (and related) technologies.

src/docs/asciidoc/overview.adoc

@@ -4,7 +4,6 @@
 :api-spring-framework: {doc-root}/spring-framework/docs/{spring-version}/javadoc-api/org/springframework
 :toc: left
 :toclevels: 2
-ifdef::backend-pdf[:source-highlighter: rouge]
 
 
 

src/docs/asciidoc/testing.adoc

@@ -5,7 +5,6 @@
 :doc-spring-boot: {doc-root}/spring-boot/docs/current/reference
 :toc: left
 :toclevels: 2
-ifdef::backend-pdf[:source-highlighter: rouge]
 
 The adoption of the test-driven-development (TDD) approach to software
 development is certainly advocated by the Spring team, and so coverage of Spring's

src/docs/asciidoc/web.adoc

@@ -4,7 +4,6 @@
 :api-spring-framework: {doc-root}/spring-framework/docs/{spring-version}/javadoc-api/org/springframework
 :toc: left
 :toclevels: 2
-ifdef::backend-pdf[:source-highlighter: rouge]
 
 This part of the reference documentation covers Spring Framework's support for the
 presentation tier (and specifically web-based presentation tiers) including support