🐛 Fix client hints URL parameter construction in mapp_intelligence (#40523)

Consolidate separate param-name and value variables into single segment
variables that include the & separator only when the value is present,
preventing malformed &= fragments in the tracking URL when client hints
are disabled.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: Shihua Zheng <powerivq@users.noreply.github.com>

Author: 3 people