Fixed handling maxAppendLimit

maxLimit prevented using numeric_limits<uint64_t>::max as a way to let
telemetry service deduce appendLimit. This commit fixes constrain to
allow passing this special value.

Tested:
  - Added new unit tests that confirm numeric_limits<uint64_t>::max is
    correctly handled in telemetry service

Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
Change-Id: I5d67e83475cdfcbb58a71b783ac9eef1e5ad7010
diff --git a/src/report_manager.cpp b/src/report_manager.cpp
index 8687316..f5dc105 100644
--- a/src/report_manager.cpp
+++ b/src/report_manager.cpp
@@ -144,7 +144,8 @@
             "Reached maximal report count");
     }
 
-    if (appendLimit > maxAppendLimit)
+    if (appendLimit > maxAppendLimit &&
+        appendLimit != std::numeric_limits<uint64_t>::max())
     {
         throw sdbusplus::exception::SdBusError(
             static_cast<int>(std::errc::invalid_argument),