Remove two Maven repositories that we no longer use for anything

We used to use these to find various Eclipse packages, but that was
always a dodgy affair since we never quite knew whether we had
matching versions of everything.  Now that we are using the
"com.diffplug.gradle.p2.asmaven" plug-in, though, we have much better
control over getting exactly the Eclipse material we need.  These two
Maven repositories no longer provide anything we use, and therefore
can be removed.

build.gradle

@@ -73,12 +73,6 @@ subprojects { subproject ->
 
 	repositories {
 		mavenCentral()
-		maven {
-			url 'https://artifacts.alfresco.com/nexus/content/repositories/public/'
-		}
-		maven {
-			url 'https://repo.eclipse.org/content/groups/releases/'
-		}
 		maven {
 			url "$rootProject.buildDir/p2asmaven/maven"
 		}