Changing the legocastle run to use valgrind_test instead of _check

Summary:
valgrind_test is the correct way to run valgrind tests.
this is becasue we need to force DISABLE_JEMALLOC

Test Plan: Running sandcastle and contrun

Reviewers: IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D65451

build_tools/rocksdb-lego-determinator

@@ -548,7 +548,7 @@ VALGRIND_TEST_COMMANDS="[
             {
                 'name':'Run RocksDB debug unit tests',
                 'timeout': 86400,
-                'shell':'$DISABLE_JEMALLOC $SHM $DEBUG make $PARALLELISM valgrind_check || $CONTRUN_NAME=valgrind_check $TASK_CREATION_TOOL',
+                'shell':'$SHM $DEBUG make $PARALLELISM valgrind_test || $CONTRUN_NAME=valgrind_check $TASK_CREATION_TOOL',
                 'user':'root',
                 $PARSER
             },