drop node 0.12 and 3 distribtests

tools/run_tests/artifacts/distribtest_targets.py

@@ -349,5 +349,5 @@ def targets():
             NodeDistribTest('linux', 'x64', os, version)
             for os in ('wheezy', 'jessie', 'ubuntu1204', 'ubuntu1404',
                        'ubuntu1504', 'ubuntu1510', 'ubuntu1604')
-            for version in ('0.12', '3', '4', '5')
+            for version in ('4', '5')
           ]