Update azure monitor otel exporter to OTel 1.15

[jeremydvoss]

• Updated log symbols. Update log symbol names open-telemetry/opentelemetry-python#2943
• Severity moved to API. g/set_logger_provider moved from SDK to internal API. Update logging to include logging api as per specification open-telemetry/opentelemetry-python#3038

Description

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• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
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[azure-sdk]

API change check

API changes are not detected in this pull request.

[jeremydvoss]

I left "The pull request does not introduce [breaking changes]" unchecked. While this pr does not affect the api layer, the version of OTel we are moving to does contain changes to some class paths and names. So, if a user is using this upcoming version of the exporter and also using OTel directly, they may need to update some of their imports from Otel's sdk and api