Revert "Upgrade jcodings dependency to 1.0.44 (elastic#43334)"

This reverts commit 08a3549 and adds a
test that demonstrates that grok with ignore case fails with the new
dependency (jcodings 1.0.44 has a breaking change compared to 1.0.12,
also requiring an upgrade of joni).

libs/grok/build.gradle

@@ -20,7 +20,7 @@
 dependencies {
     compile 'org.jruby.joni:joni:2.1.6'
     // joni dependencies:
-    compile 'org.jruby.jcodings:jcodings:1.0.44'
+    compile 'org.jruby.jcodings:jcodings:1.0.12'
 
     testCompile(project(":test:framework")) {
         exclude group: 'org.elasticsearch', module: 'elasticsearch-grok'

libs/grok/licenses/jcodings-1.0.12.jar.sha1

@@ -0,0 +1 @@
+6bc17079fcaa8823ea8cd0d4c66516335b558db8

modules/ingest-common/src/test/java/org/elasticsearch/ingest/common/GrokProcessorTests.java

@@ -45,6 +45,16 @@ public void testMatch() throws Exception {
         assertThat(doc.getFieldValue("one", String.class), equalTo("1"));
     }
 
+    public void testIgnoreCase() throws Exception {
+        String fieldName = RandomDocumentPicks.randomFieldName(random());
+        IngestDocument doc = RandomDocumentPicks.randomIngestDocument(random(), new HashMap<>());
+        doc.setFieldValue(fieldName, "A");
+        GrokProcessor processor = new GrokProcessor(randomAlphaOfLength(10), Collections.emptyMap(),
+            Collections.singletonList("(?<a>(?i)A)"), fieldName, false, false, ThreadWatchdog.noop());
+        processor.execute(doc);
+        assertThat(doc.getFieldValue("a", String.class), equalTo("A"));
+    }
+
     public void testNoMatch() {
         String fieldName = RandomDocumentPicks.randomFieldName(random());
         IngestDocument doc = RandomDocumentPicks.randomIngestDocument(random(), new HashMap<>());