chore(observability)!: Remove deprecated HTTP metrics (#19447)

* chore(observability)!: Remove deprecated HTTP metrics

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>

* Add upgrade guide note

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>

* Remove deprecated metrics from website

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>

* Bump log level of logplex request received log down to debug

To match other "request received" log levels.

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>

* Use our crate::http::HttpClient rather than hyper::Client for aws_ecs_metrics source

To ensure we get the same instrumentation.

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>

* Update website/content/en/highlights/2023-12-19-0-35-0-upgrade-guide.md

Co-authored-by: DeForest Richards <56796055+drichards-87@users.noreply.github.com>

* cue fixes

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>

* Format with cue 0.5.0

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>

* Update internal events for apache_metrics and aws_ecs_metrics

Reuse existing HttpClient errors.

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>

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Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>
Co-authored-by: DeForest Richards <56796055+drichards-87@users.noreply.github.com>