Fix macOS CI: trust microsoft/mssql-release tap for Homebrew 5.2+ (#4363)

* Fix macOS CI: trust microsoft/mssql-release tap for Homebrew 5.2+

Homebrew 5.2.0 made untrusted-tap enforcement the default. After
'brew update' pulls in the new version, 'brew install mssql-tools18'
is refused because the microsoft/mssql-release tap is untrusted.

This caused sqlcmd to never be installed (exit code 127), so the
SQL Server connectivity check looped for 72 attempts and failed.

Add 'brew trust microsoft/mssql-release' after tapping and before
'brew update' to explicitly trust the Microsoft tap.

* Address PR #4363 review feedback

- Move 'brew trust' after 'brew update' so it works even when the
  runner image starts with a Homebrew version older than 5.2.
- Add a fail-fast check after 'brew install mssql-tools18' to
  immediately abort with a clear error if sqlcmd is not on PATH,
  avoiding the 6-minute timeout loop.

Author: paulmedynski

eng/pipelines/common/templates/steps/configure-sql-server-macos-step.yml

@@ -34,8 +34,19 @@ steps:
       brew install docker
       brew tap microsoft/mssql-release https://github.com/Microsoft/homebrew-mssql-release
       brew update
+      # Homebrew 5.2+ requires explicit trust for third-party taps.  Run this
+      # after 'brew update' so the trust command is available even if the runner
+      # image shipped an older Homebrew version.
+      brew trust microsoft/mssql-release
       HOMEBREW_ACCEPT_EULA=Y brew install mssql-tools18
 
+      # Fail fast if sqlcmd was not installed (e.g. tap-trust or formula error).
+      # Without this check the script would loop for ~6 minutes trying to connect.
+      if ! command -v sqlcmd &>/dev/null; then
+        echo "ERROR: sqlcmd is not on PATH after brew install. Check the mssql-tools18 installation above."
+        exit 1
+      fi
+
       # Start Colima with Virtualization.framework for x86_64 binary translation
       # on Apple Silicon.  Rosetta/binfmt emulation is enabled by default in
       # Colima >= 0.8 when using --vm-type vz, which is dramatically faster than