What does this PR do?

• Obfuscates query strings on http client span tags via a default regex and allows customization of this regex
• Re-enables query string collection on http client spans by default (disabled by default in contrib/net/http: Make DD_TRACE_HTTP_CLIENT_TAG_QUERY_STRING false by default #3010)

Passes tests in: DataDog/system-tests#3783

Motivation

Http server spans already benefited from both of the above behaviors. Now, http client spans can too (safely).

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.
• For internal contributors, a matching PR should be created to the v2-dev branch and reviewed by @DataDog/apm-go.

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