[8.6] [Renderers] always include baseTheme with charts theme (#145401)

[kibanamachine]

Backport

This will backport the following commits from main to 8.6:

• [Renderers] always include baseTheme with charts theme (#145401)

Questions ?

Please refer to the Backport tool documentation

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: b889a62

Failed CI Steps

• FTR Configs #9

Test Failures

• [job] [logs] FTR Configs #9 / Spaces app Spaces Space Navigation Menu allows user to navigate to different spaces

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
expressionGauge	18.7KB	18.7KB	+33.0B
expressionHeatmap	91.3KB	91.3KB	+33.0B
expressionMetricVis	73.5KB	73.6KB	+92.0B
total			+158.0B

Unknown metric groups

ESLint disabled in files

id	before	after	diff
osquery	1	2	+1

ESLint disabled line counts

id	before	after	diff
enterpriseSearch	19	21	+2
fleet	59	65	+6
osquery	108	113	+5
securitySolution	441	447	+6
total			+19

Total ESLint disabled count

id	before	after	diff
enterpriseSearch	20	22	+2
fleet	67	73	+6
osquery	109	115	+6
securitySolution	518	524	+6
total			+20

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @andrewctate