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

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.

Add 'brew trust microsoft/mssql-release' after 'brew update' to
explicitly trust the Microsoft tap (placed after update so the trust
command is available even on older runner images).

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