[ci][amd] fix basic models extra init test (#28676)

Signed-off-by: Bradley Davis <bradleyhd@meta.com>

.buildkite/scripts/hardware_ci/run-amd-test.sh

@@ -180,10 +180,10 @@ fi
 # check if the command contains shard flag, we will run all shards in parallel because the host have 8 GPUs.
 if [[ $commands == *"--shard-id="* ]]; then
   # assign job count as the number of shards used
-  commands=${commands//"--num-shards= "/"--num-shards=${PARALLEL_JOB_COUNT} "}
+  commands=$(echo "$commands" | sed -E "s/--num-shards[[:blank:]]*=[[:blank:]]*[0-9]*/--num-shards=${PARALLEL_JOB_COUNT} /g" | sed 's/ \\ / /g')
   for GPU in $(seq 0 $(($PARALLEL_JOB_COUNT-1))); do
     # assign shard-id for each shard
-    commands_gpu=${commands//"--shard-id= "/"--shard-id=${GPU} "}
+    commands_gpu=$(echo "$commands" | sed -E "s/--shard-id[[:blank:]]*=[[:blank:]]*[0-9]*/--shard-id=${GPU} /g" | sed 's/ \\ / /g')
     echo "Shard ${GPU} commands:$commands_gpu"
     echo "Render devices: $BUILDKITE_AGENT_META_DATA_RENDER_DEVICES"
     docker run \