[Aggs Based] Heatmap renders title labels on chart

[nickofthyme]

Kibana version:

8.10 or sooner

Describe the bug:

When a user goes to create a heatmap split chart on the agg-based vis library with only an X-Axis bucket. If they do not specify a Y-Axis bucket, the labels of the split will be rendered on top of the chart.

Steps to reproduce:

1. Create aggs based chart with split and x-axis buckets (see example in screenshot below)
2. Notice the labels on top of the chart

Expected behavior:

Labels are rendered in the axis as necessary

Screenshots (if relevant):

Any additional context:
This is an issue in the configuration of the chart and depends on the xAxisTitle property on whether to render the values. In this case the axis is size correctly but the labels are still being rendered when they. shouldn't be.

[elasticmachine]

Pinging @elastic/kibana-visualizations (Team:Visualizations)

[stratoula]

Let's solve this before removing vislib heatmap from kibana

[nickofthyme]

Agreed, also would be nice to fix elastic/elastic-charts#1168 (comment) before removing it also.