[8.x](backport #4242) [APM] Remove limitation about host metrics in otel docs (#4263)

* remove limitation about host metrics in otel docs (#4242)

(cherry picked from commit 498f14d)

* Delete docs/en/serverless directory

---------

Co-authored-by: Colleen McGinnis <[email protected]>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Author: 3 people

docs/en/observability/apm/otel-limitations.asciidoc

@@ -9,12 +9,6 @@
 * Inability to see Stack traces in spans.
 * Inability in APM views to view the "Time Spent by Span Type"  (see issue https://github.com/elastic/apm-server/issues/5747[#5747]).
 
-[float]
-[[apm-open-telemetry-metrics-limitations]]
-==== OpenTelemetry metrics
-
-* Inability to see host metrics in Elastic Metrics Infrastructure view when using the OpenTelemetry Collector host metrics receiver (see issue https://github.com/elastic/apm-server/issues/5310[#5310]).
-
 [float]
 [[apm-open-telemetry-logs-intake]]
 ==== OpenTelemetry logs