Exclude commons-logging from spring-test dependencies

Prior to this commit, various dependencies in the spring-test module
pulled in commons-logging as a transitive dependency. Consequently,
the presence of commons-logging in the generated Eclipse classpath
overrode the intended use of the spring-jcl module causing JUL to be
used instead of log4j for tests executed within Eclipse, thereby
ignoring the configuration in src/test/resources/log4j2-test.xml.

This commit addresses this issue by excluding commons-logging in
spring-test.gradle for all Selenium dependencies.

Issue: SPR-15930

spring-test/spring-test.gradle

@@ -45,8 +45,11 @@ dependencies {
 	optional("net.sourceforge.htmlunit:htmlunit:2.27") {
 		exclude group: "commons-logging", module: "commons-logging"
 	}
-	optional("org.seleniumhq.selenium:htmlunit-driver:2.27")
+	optional("org.seleniumhq.selenium:htmlunit-driver:2.27") {
+		exclude group: "commons-logging", module: "commons-logging"
+	}
 	optional("org.seleniumhq.selenium:selenium-java:3.4.0") {
+		exclude group: "commons-logging", module: "commons-logging"
 		exclude group: "io.netty", module: "netty"
 	}
 	optional("org.xmlunit:xmlunit-matchers:2.3.0")