[llvm-profgen] Turn off cold context trimming by default

We merge cold context by default to save profile size. However trimming cold context after merging doesn't save size much, so default to off to reflect how it's commonly used.

Differential Revision: https://reviews.llvm.org/D109166

Author: WenleiHe

llvm/tools/llvm-profgen/ProfileGenerator.cpp

@@ -46,7 +46,7 @@ static cl::opt<bool> CSProfMergeColdContext(
              "profile."));
 
 static cl::opt<bool> CSProfTrimColdContext(
-    "csprof-trim-cold-context", cl::init(true), cl::ZeroOrMore,
+    "csprof-trim-cold-context", cl::init(false), cl::ZeroOrMore,
     cl::desc("If the total count of the profile after all merge is done "
              "is still smaller than threshold, it will be trimmed."));