test(profiling): unset DD_SITE variable in agentless URL check [backport 1.17]

[github-actions]

Backport edac03b from #6642 to 1.17.

A test for the profiler exporter in agentless mode required the DD_SITE variable to be unset. We modify the test to ensure that this variable is unset in the subprocess to exercise and test the correct logic.

Checklist

• Change(s) are motivated and described in the PR description.
• Testing strategy is described if automated tests are not included in the PR.
• Risk is outlined (performance impact, potential for breakage, maintainability, etc).
• Change is maintainable (easy to change, telemetry, documentation).
• Library release note guidelines are followed. If no release note is required, add label changelog/no-changelog.
• Documentation is included (in-code, generated user docs, public corp docs).
• Backport labels are set (if applicable)

Reviewer Checklist

• Title is accurate.
• No unnecessary changes are introduced.
• Description motivates each change.
• Avoids breaking API changes unless absolutely necessary.
• Testing strategy adequately addresses listed risk(s).
• Change is maintainable (easy to change, telemetry, documentation).
• Release note makes sense to a user of the library.
• Reviewer has explicitly acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment.
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[pr-commenter]

Benchmarks

Benchmark execution time: 2023-08-11 16:59:38

Comparing candidate commit 3931401 in PR branch backport-6642-to-1.17 with baseline commit ff8ab1c in branch 1.17.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 94 metrics, 0 unstable metrics.