Merge pull request github#18999 from michaelnebel/csharp/ccr-constant-condition

C#: Add cs/constant-condition to the CCR suite.

Author: michaelnebel

csharp/ql/src/codeql-suites/csharp-ccr.qls

@@ -9,3 +9,4 @@
       - cs/inefficient-containskey
       - cs/call-to-object-tostring
       - cs/local-not-disposed
+      - cs/constant-condition