Fix stale/broken hardcoded release-stream URLs in install_sdp.sh, and point them at 'main' permanently instead.
SDPURL had a real bug (r25-1 hyphen, doesn't match any real stream name)
plus staleness (r25.1, not the upcoming release); ThisScriptURL, the
get_p4_binaries.sh usage example, and the OrgName/ServerID doc-comment
links were just stale (r25.1).
Rather than bake in the upcoming release stream's name (which would only
be a temporary fix, requiring a second edit once the real GA name is
known, and would 404 until that stream actually exists), point all of
these at the 'main' stream instead. main's downloads/ will become
isolate'd and always carry a real, current tarball (see the release
process doc's updated Package step) -- so this URL is now permanent,
never needs per-release editing, and mirrors the fixed download location
the Classic depot always had. install_sdp.sh itself isn't isolated, so
main's copy of the script is already correct immediately after Copy Up
with no such gap.
Agent: Claude Code, Model: Claude Sonnet 5 (claude-sonnet-5), operating as bot_Claude_Anthropic.