### Elasticsearch Version

8.1.1.

### Installed Plugins

non

### Java Version

_bundled_

### OS Version

ESS

### Problem Description

When searching for any term in Kibana the highlighting works on any field type except `match_only_text` which has become the default field type in ~7.14 for all of the beats and Elastic Agent integrations.
E.g. here it does not work:
![image](https://user-images.githubusercontent.com/12175559/160823534-7cad2e0e-b898-4a15-9376-1c2993d261bb.png)
E.g. on 7.17 using text and keyword fields:
![image](https://user-images.githubusercontent.com/12175559/160823810-a6024e92-f062-4e39-a399-41c5d087fcdd.png)

Discussed this with @romseygeek already. seems that the highlighter is not capeable of dealing with the specialized match_only_text field type.


### Steps to Reproduce

Index something using a `match_only_text` field.
Run a search on it. It should be highlighted.



### Logs (if relevant)

_No response_
server/src/main/java/org/elasticsearch/search/fetch/subphase/highlight/HighlightPhase.java
);
        return new FetchSubPhaseProcessor() {
            @Override
            public void setNextReader(LeafReaderContext readerContext) {
            }
            @Override
            public void process(HitContext hitContext) throws IOException {
                Map<String, HighlightField> highlightFields = new HashMap<>();
                for (String field : contextBuilders.keySet()) {
                    FieldHighlightContext fieldContext = contextBuilders.get(field).apply(hitContext);
                    Highlighter highlighter = getHighlighter(fieldContext.field);
                    HighlightField highlightField = highlighter.highlight(fieldContext);
                    if (highlightField != null) {
                        
                        
                        
                        highlightFields.put(field, new HighlightField(field, highlightField.fragments()));
                    }
                }
                hitContext.hit().highlightFields(highlightFields);
            }
        };
    }
    private Highlighter getHighlighter(SearchHighlightContext.Field field) {
        String highlighterType = field.fieldOptions().highlighterType();
        if (highlighterType == null) {
            highlighterType = "unified";
        }
        Highlighter highlighter = highlighters.get(highlighterType);
        if (highlighter == null) {