driver: improve RE matching case

[lance6716]

as the comment in #1104 (comment)

[lance6716]

@dveeden PTAL

[Copilot]

Pull request overview

This PR refines the DSN compatibility rewrite used by the driver package so that tcp(...) host rewriting only applies to the host portion (avoiding accidental rewrites in credentials/query), and expands test coverage for tricky DSN inputs.

Changes:

• Tighten compatDSNre to be anchored and only rewrite the host tcp(...) segment.
• Update the rewrite replacement to preserve the mysql:// prefix and optional userinfo.
• Add DSN parsing tests for parentheses in query params and tcp(...) appearing in passwords.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
driver/driver.go	Updates the compatibility regexp and replacement logic for tcp(...) DSN host rewriting.
driver/driver_test.go	Adds new DSN parsing test cases to validate the improved matching behavior.

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[lance6716]

Addressed Copilot comments: switched replacement to `` and added a DSN parse test for tcp(...) host without credentials (e.g. `tcp(127.0.0.1:3310)/db`).

[lance6716]

@dveeden PTAL