XRAY-146567 - Fixed maven proxy issue

[gauriy-tech]

• The pull request is targeting the dev branch.
• The code has been validated to compile successfully by running go vet ./....
• The code has been formatted properly using go fmt ./....
• All static analysis checks passed.
• All tests have passed. If this feature is not already covered by the tests, new tests have been added.
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• All changes are detailed at the description. if not already covered at JFrog Documentation, new documentation have been added.

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Curation-audit's temp settings.xml for Maven was rendered from scratch, dropping any configuration from the customer's real ~/.m2/settings.xml. This broke dependency resolution for customers whose Artifactory is only reachable through a corporate proxy, since Maven only reads proxy config from the active settings.xml (not env vars or JVM system-proxy flags).

The temp settings.xml is now seeded from the user's existing file (when present) and only upserts the curation-specific server/mirror/profile entries on top, under a dedicated jfrog-curation-audit id — preserving and any other existing config untouched. Falls back to the original template when no user settings.xml exists, so behavior for unaffected customers is unchanged.