[releng] Disable the maven-toolchains-plugin

Recent versions of Eclipse (starting from 2020-09 for the Help system,
2020-12 for the platform itself via p2) require Java 11. We need to
run the EMF Transaction tests under these more recent (well, less
ancient) versions of Java. Disable the toolchains plugin which
otherwise forces the use of a JRE 1.8 even when executing the build
under Java 11 or later.

Change-Id: I22e00e8c599a7b6b8e176cba04d23b726a3e41aa
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>

org.eclipse.emf.transaction.releng/pom.xml

@@ -34,25 +34,6 @@
 
 	<build>
 		<plugins>
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-toolchains-plugin</artifactId>
-				<version>3.0.0</version>
-				<executions>
-					<execution>
-						<goals>
-							<goal>toolchain</goal>
-						</goals>
-					</execution>
-				</executions>
-				<configuration>
-					<toolchains>
-						<jdk>
-							<id>JavaSE-1.8</id>
-						</jdk>
-					</toolchains>
-				</configuration>
-			</plugin>
 			<plugin>
 				<groupId>org.eclipse.tycho</groupId>
 				<artifactId>tycho-maven-plugin</artifactId>