Consume JGit artifacts from Maven Central

The recent JGit releases were published to the Eclipse repository
due to a security embargo. The embargo has since been lifted, and
the releases are available on Maven Central, so switch back to
consuming the artifacts from there.

This update was already done on the stable branches stable-2.9 to
stable-2.12 by change I054cc91f4, but was lost during the merge to
stable-2.13 in change Ib5243b6d2.

Change-Id: I55bbff5b0c738e9f419949d29b68b7cc88a748a7
diff --git a/lib/JGIT_VERSION b/lib/JGIT_VERSION
index 12e3cfb..7d1e527 100644
--- a/lib/JGIT_VERSION
+++ b/lib/JGIT_VERSION
@@ -1,6 +1,6 @@
 include_defs('//lib/maven.defs')
 
-REPO = ECLIPSE # Leave here even if set to MAVEN_CENTRAL.
+REPO = MAVEN_CENTRAL # Leave here even if set to MAVEN_CENTRAL.
 VERS = '4.5.5.201812240535-r'
 DOC_VERS = VERS # Set to VERS unless using a snapshot
 JGIT_DOC_URL="http://download.eclipse.org/jgit/site/" + DOC_VERS + "/apidocs"