fix: set traceContextInjection param for E2E test case

[ganeshnj]

What and why?

❌ /Users/vagrant/git/Datadog/E2ETests/Tracing/TracerE2ETests.swift:54:84: missing argument for parameter 'traceContextInjection' in call
        let anyWriter = HTTPHeadersWriter(samplingStrategy: .custom(sampleRate: 20))

How?

Set arg value.

Review checklist

• Feature or bugfix MUST have appropriate tests (unit, integration)
• Make sure each commit and the PR mention the Issue number or JIRA reference
• Add CHANGELOG entry for user facing changes

Custom CI job configuration (optional)

• Run unit tests for Core, RUM, Trace, Logs, CR and WVT
• Run unit tests for Session Replay
• Run integration tests
• Run smoke tests
• Run tests for tools/

[datadog-datadog-prod-us1]

Datadog Report

Branch report: ganeshnj/fix/trace-context-injection-param
Commit report: 3145106
Test service: dd-sdk-ios

✅ 0 Failed, 3222 Passed, 0 Skipped, 2m 14.12s Total Time
🔻 Test Sessions change in coverage: 9 decreased, 4 increased

🔻 Code Coverage Decreases vs Default Branch (9)

This report shows up to 5 code coverage decreases.

• test DatadogCrashReportingTests tvOS 27.39% (-0.32%) - Details
• test DatadogCrashReportingTests iOS 27.36% (-0.3%) - Details
• test DatadogLogsTests iOS 46.09% (-0.26%) - Details
• test DatadogLogsTests tvOS 46.16% (-0.24%) - Details
• test DatadogWebViewTrackingTests iOS 18.31% (-0.21%) - Details