[Feature] [Epic] - Migrate EUM metrics to OpenTelemetry

[EddeCCC]

Is your feature request related to a problem? Please describe.
We are already using OpenTelemetry to create traces and export data. However, we are currently still using OpenCensus to generate the EUM metrics themselves. In future, these should be generated with OpenTelemetry instead.

Describe the solution you'd like
Remove the opencensusshim and use OpenTelemetry to create metrics.
In parallel operation of two different EUM servers (OpenCensus vs OpenTelemetry) the correctness of the generated metrics will be validated.

[EddeCCC]

In addition to inspectIT/inspectit-ocelot#1336, we will have to migrate the EUM server to OTel metrics.

[EddeCCC]

Tasks:

• Update metric definition model
• Remove MetricAdapter for OTLP-Exporter
• Remove OC-Influx-Exporter
• Selfmonitoring has to use OTel scopes
• Classes have to switch to OTel metrics: MeasuresAndViewsManager, TimeWindowViewManager, TimeWindowsView, AsyncMetricRecorder, ResourceTimingBeaconRecorder
• Remove OC from BeanConfiguration (and add OTel SDK, or something like OTel-Controller from inspectit-ocelot?)
• Update tests
• Update docs
• Migration guide
• Update demo Dashboards