### Description

Our current default for the `http.max_header_size` setting is 8KB. This is lower than the current default for Kibana (16KB in 8.x, based on [the default for node 14 and up](https://www.educative.io/answers/what-is-the-node-httpmaxheadersize-property)), and our the ESS proxy (1MB based on the Go `http` library default). To align with the current convention of other Elastic components, we should increase the ES header size setting default to 16KB. Note that this limit is for all request headers combined, rather than per header.

This issue came out of an investigation around [JWT auth headers](https://www.elastic.co/guide/en/elasticsearch/reference/master/jwt-auth-realm.html) which can get quite sizeable.

I'm happy to open a PR since it's a small change.
server/src/main/java/org/elasticsearch/http/HttpTransportSettings.java
new ByteSizeValue(100, ByteSizeUnit.MB),
        new ByteSizeValue(0, ByteSizeUnit.BYTES),
        new ByteSizeValue(Integer.MAX_VALUE, ByteSizeUnit.BYTES),
        Property.NodeScope
    );
    public static final Setting<ByteSizeValue> SETTING_HTTP_MAX_CHUNK_SIZE = Setting.byteSizeSetting(
        "http.max_chunk_size",
        new ByteSizeValue(8, ByteSizeUnit.KB),
        Property.NodeScope
    );
    public static final Setting<ByteSizeValue> SETTING_HTTP_MAX_HEADER_SIZE = Setting.byteSizeSetting(
        "http.max_header_size",
        new ByteSizeValue(8, ByteSizeUnit.KB),
        Property.NodeScope
    );
    public static final Setting<Integer> SETTING_HTTP_MAX_WARNING_HEADER_COUNT = intSetting(
        "http.max_warning_header_count",
        -1,
        -1,
        Property.NodeScope
    );
    public static final Setting<ByteSizeValue> SETTING_HTTP_MAX_WARNING_HEADER_SIZE = Setting.byteSizeSetting(
        "http.max_warning_header_size",
        new ByteSizeValue(-1),
        Property.NodeScope
    );
    public static final Setting<ByteSizeValue> SETTING_HTTP_MAX_INITIAL_LINE_LENGTH = Setting.byteSizeSetting(
        "http.max_initial_line_length",
        new ByteSizeValue(4, ByteSizeUnit.KB),
        Property.NodeScope