scripted-diff: rename pszThread to thread_name

Since it is now a string_view instead of a const char*, update the
name to reflect that the variable is no longer a "Pointer to
String, Zero-terminated" (psz).

-BEGIN VERIFY SCRIPT-
sed -i s/pszThread/thread_name/ $(git grep -l pszThread src)
-END VERIFY SCRIPT-

src/util/system.h

@@ -51,7 +51,7 @@ bool error(const char* fmt, const Args&... args)
     return false;
 }
 
-void PrintExceptionContinue(const std::exception* pex, std::string_view pszThread);
+void PrintExceptionContinue(const std::exception* pex, std::string_view thread_name);
 
 /**
  * Ensure file contents are fully committed to disk, using a platform-specific