chore(trace-exporter): disable data pipeline when SSI is enabled (#7386)

## Summary of changes

## Reason for change

To avoid any surprises.

## Implementation details

Just like other checks we conditionally disable trace exporter for
certain platforms and situations, disable trace exporter when SSI in
works.

## Test coverage

## Other details

Fixes https://datadoghq.atlassian.net/browse/APMSP-2197

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Author: ganeshnj

tracer/src/Datadog.Trace/Configuration/TracerSettings.cs

@@ -453,6 +453,17 @@ internal TracerSettings(IConfigurationSource? source, IConfigurationTelemetry te
 
                     _telemetry.Record(ConfigurationKeys.TraceDataPipelineEnabled, false, ConfigurationOrigins.Calculated);
                 }
+
+                // SSI already utilizes libdatadog. To prevent unexpected behavior,
+                // we proactively disable the data pipeline when SSI is enabled. Theoretically, this should not cause any issues,
+                // but as a precaution, we are taking a conservative approach during the initial rollout phase.
+                if (!string.IsNullOrEmpty(EnvironmentHelpers.GetEnvironmentVariable("DD_INJECTION_ENABLED")))
+                {
+                    DataPipelineEnabled = false;
+                    Log.Warning(
+                        $"{ConfigurationKeys.TraceDataPipelineEnabled} is enabled, but SSI is enabled. Disabling data pipeline.");
+                    _telemetry.Record(ConfigurationKeys.TraceDataPipelineEnabled, false, ConfigurationOrigins.Calculated);
+                }
             }
 
             // We should also be writing telemetry for OTEL_LOGS_EXPORTER similar to OTEL_METRICS_EXPORTER, but we don't have a corresponding Datadog config