Only use Host header from reverse proxy (#32060)

X-Forwarded-Host has many problems: non-standard, not well-defined
(X-Forwarded-Port or not), conflicts with Host header, it already caused
problems like #31907. So do not use X-Forwarded-Host, just use Host
header directly.

Official document also only uses `Host` header and never mentioned
others.

.github/workflows/pull-db-tests.yml

@@ -201,7 +201,8 @@ jobs:
     runs-on: ubuntu-latest
     services:
       mssql:
-        image: mcr.microsoft.com/mssql/server:2017-latest
+        # some images before 2024-04 can't run on new kernels
+        image: mcr.microsoft.com/mssql/server:2019-latest
         env:
           ACCEPT_EULA: Y
           MSSQL_PID: Standard