Migrate from OpenCensus library

[tiffanny29631]

The migration replaces OpenCensus libraries with OpenTelemetry SDK while preserving:

• Metric names, type and descriptions
• Recording patterns
• Pipeline architecture and data flow
• Sidecar configurations
• Export destinations (Prometheus, Cloud Monitoring, Cloud Monarch)

Key Changes

1. Library Dependencies

Before (OpenCensus):

import (
    "go.opencensus.io/stats"
    "go.opencensus.io/stats/view"
    "go.opencensus.io/tag"
    "contrib.go.opencensus.io/exporter/ocagent"
)

After (OpenTelemetry):

import (
    "go.opentelemetry.io/otel"
    "go.opentelemetry.io/otel/metric"
    "go.opentelemetry.io/otel/attribute"
    "go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
    "go.opentelemetry.io/otel/sdk/metric"
    "go.opentelemetry.io/otel/sdk/resource"
)

2. Metric Instrument Types

OpenCensus	OpenTelemetry	Description
stats.Int64	metric.Int64Counter	Counter metrics
stats.Int64	metric.Int64Gauge	Gauge metrics
stats.Float64	metric.Float64Histogram	Histogram metrics

3. Recording Patterns

Before (OpenCensus):

stats.Record(ctx, measurement)

After (OpenTelemetry):

instrument.Record(ctx, value, metric.WithAttributes(attrs...))

4. Tag/Attribute System

Before (OpenCensus):

tagCtx, _ := tag.New(ctx, tag.Upsert(KeyStatus, "success"))

After (OpenTelemetry):

attrs := []attribute.KeyValue{
    attribute.String("status", "success"),
}

5. Exporter Configuration

Before (OpenCensus):

oce, err := ocagent.NewExporter(ocagent.WithInsecure())

After (OpenTelemetry):

exporter, err := otlpmetricgrpc.New(
    context.Background(),
    otlpmetricgrpc.WithInsecure(),
    otlpmetricgrpc.WithEndpoint("otel-collector:4317"),
)

[google-oss-prow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please ask for approval from tiffanny29631. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[tiffanny29631]

/test all

[tiffanny29631]

/test all