Add default MALLOC_CONF env (#26352)

Signed-off-by: Nxige-16 <xi.ge@zilliz.com>

build/docker/milvus/amazonlinux2023/Dockerfile

@@ -25,6 +25,7 @@ COPY ./lib/ /milvus/lib/
 ENV PATH=/milvus/bin:$PATH
 ENV LD_LIBRARY_PATH=/milvus/lib:$LD_LIBRARY_PATH:/usr/lib
 ENV LD_PRELOAD=/milvus/lib/libjemalloc.so
+ENV MALLOC_CONF=background_thread:true
 
 # Add Tini
 ADD https://github.com/krallin/tini/releases/download/v0.19.0/tini-$TARGETARCH /tini

build/docker/milvus/gpu/ubuntu20.04/Dockerfile

@@ -21,3 +21,4 @@ COPY ./lib/ /milvus/lib/
 ENV PATH=/milvus/bin:$PATH
 ENV LD_LIBRARY_PATH=/milvus/lib:$LD_LIBRARY_PATH:/usr/lib
 ENV LD_PRELOAD=/milvus/lib/libjemalloc.so
+ENV MALLOC_CONF=background_thread:true

build/docker/milvus/ubuntu20.04/Dockerfile

@@ -27,6 +27,7 @@ COPY ./lib/ /milvus/lib/
 ENV PATH=/milvus/bin:$PATH
 ENV LD_LIBRARY_PATH=/milvus/lib:$LD_LIBRARY_PATH:/usr/lib
 ENV LD_PRELOAD=/milvus/lib/libjemalloc.so
+ENV MALLOC_CONF=background_thread:true
 
 # Add Tini
 ADD https://github.com/krallin/tini/releases/download/v0.19.0/tini-$TARGETARCH /tini