Kotlin: Disable the custom plugin test for now

Author: igfoo

…tests/kotlin/linux/custom_plugin/test.py …lin/linux/custom_plugin/test.py-disabledjava/ql/integration-tests/kotlin/linux/custom_plugin/test.py renamed to java/ql/integration-tests/kotlin/linux/custom_plugin/test.py-disabled java/ql/integration-tests/kotlin/linux/custom_plugin/test.py renamed to java/ql/integration-tests/kotlin/linux/custom_plugin/test.py-disabled

@@ -3,6 +3,8 @@
 import commands
 
 
+# This test is temporarily disabled
+
 @runs_on.linux
 def test(codeql, java_full, cwd, semmle_code_dir, test_dir):
     build_dir = cwd / "build"