CI: actually run the kit in smoke tests, on oldest and newest SQL Server

The smoke test installed only the changed sp_*.sql and ran it with
@VersionCheckMode = 1, which is an unconditional early RETURN. No check body
ever executed, so runtime breakage passed green -- PR BrentOzarULTD#4045 had two such bugs
reach human review.

Now, per issue BrentOzarULTD#4046:

- Runs all 12 non-deprecated scripts through a 39-step parameter matrix
  covering the @output* table paths, sp_BlitzIndex modes 0-4, sp_kill's
  execute path and sp_DatabaseRestore. sp_BlitzUpdate is excluded because it
  rewrites the procs mid-run.
- Installs the base branch's copy of every script, runs the same matrix, and
  compares. SQL errors this branch introduces fail the build; errors already
  present on base are reported and do not. Differences in sp_Blitz findings
  are printed for review and never fail, since changing a finding is often the
  point of the change.
- Seeds a database, indexes, backup history and plan cache activity so the
  scripts have something real to read instead of an empty server.
- Runs against SQL Server 2017 (oldest in support since 2016 aged out on
  2026-07-14) and SQL Server 2025.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FMPBMMANLaFgSQ73GTgBW7

Author: BrentOzar