The pipeline defined in the bulk update item here is ignored:

```
POST /_bulk
{"update":{"_id":"1","_index":"pipeline-test","pipeline":"lowercase-pipeline"}}
{"upsert":{"myField":"UPPER"},"script":{"source":"ctx._source.myField = 'CHANGED'","lang":"painless"}}
```

Only if the pipeline is defined as query string argument, then the pipeline is picked up and used to process the upset:

```
POST /_bulk?pipeline=lowercase-pipeline
{"update":{"_id":"1","_index":"pipeline-test"}}
{"upsert":{"myField":"UPPER"},"script":{"source":"ctx._source.myField = 'CHANGED'","lang":"painless"}}
```

The Bulk API should also use the pipeline defined in the bulk update item.
server/src/main/java/org/elasticsearch/action/bulk/BulkRequestParser.java
* @param deprecateOrErrorOnType whether to allow _type information in the index line; used by BulkMonitoring
     * @param restApiVersion
     */
    public BulkRequestParser(boolean deprecateOrErrorOnType, RestApiVersion restApiVersion) {
        this.deprecateOrErrorOnType = deprecateOrErrorOnType;
        this.config = XContentParserConfiguration.EMPTY.withDeprecationHandler(LoggingDeprecationHandler.INSTANCE)
            .withRestApiVersion(restApiVersion);
    }
    private static int findNextMarker(byte marker, int from, BytesReference data) {
        final int res = data.indexOf(marker, from);
        if (res != -1) {
            assert res >= 0;
            return res;
        }
        if (from != data.length()) {
            throw new IllegalArgumentException("The bulk request must be terminated by a newline [\\n]");
        }
        return res;
    }
    /**
     * Returns the sliced {@link BytesReference}. If the {@link XContentType} is JSON, the byte preceding the marker is checked to see
     * if it is a carriage return and if so, the BytesReference is sliced so that the carriage return is ignored
     */
    private static BytesReference sliceTrimmingCarriageReturn(
        BytesReference bytesReference,
        int from,
        int nextMarker,
        XContentType xContentType
    ) {
        final int length;