Pie-chart labels overlap when chart is split in columns

[EmilBode]

Kibana version:
7.5.1

Elasticsearch version:
7.5.1

Server OS version:
Kibana server: Windows 10
Elastic server: Ubuntu 18.04.3 LTS

Browser version:
Chrome 70.0.3538.77 (64-bit)

Browser OS version:
Windows 10

Original install method (e.g. download page, yum, from source, etc.):
Download

Describe the bug:
When creating a pie-chart visualization, and splitting the charts into columns, labels from the different parts overlap

Steps to reproduce:
With this data:

PUT test/_doc/1
{
  "a": 1,
  "b": "gfdjklgsdhklghsdjkl"
}
PUT test/_doc/2
{
  "a": 2,
  "b": "ghdfjskghsdjkghjrsbhuprios"
}
PUT test/_doc/3
{
  "a": 1,
  "b": "hfdjkslgnfsdjklgfjkgwuibvfsdjklnv"
}
PUT test/_doc/4
{
  "a": 2,
  "b": "fghsdjklhgjkldshfg"
}

Create a new pie-chart visualization:

• Split chart in columns by terms-aggregation on field a
• Split into slices by terms on field b.keyword
• Turn on "show labels" under options
  ** Observed behavior **
  Labels coming from different pies overlap

Expected behavior:
That labels from different slices never overlap,

Screenshots (if relevant):

(Arrow added for clarity)

Any additional context:

• Seems to be a problem only with somewhat longer labels
• Additionally, some labels end up being truncated by borders/legend, though this may be less of a problem (it's impossible to support arbitrarily long labels)

[monfera]

@EmilBode we're working on rolling out elastic-charts partitioning charts, which attempt to fill text inside the pie slices or ring sectors, see some examples under Sunburst and Treemap, eg. this one

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)