preserve tmp mountpoint on reset

scripts/soak/run_soak.sh

@@ -466,6 +466,12 @@ move_if_exists() {
   fi
 }
 
+clear_dir_contents() {
+  local dir_path="$1"
+  [[ -d "$dir_path" ]] || return 0
+  find "$dir_path" -mindepth 1 -maxdepth 1 -exec rm -rf {} +
+}
+
 db_state_exists() {
   [[ -e "$DB_DIR/work-db" || -e "$DB_DIR/repo-bytes.db" ]]
 }
@@ -486,7 +492,7 @@ isolate_state_after_failure() {
     INVALID_TMP_PATH="$TMP_DIR"
     TMP_CLEANUP_STATUS="pending"
     TMP_CLEANUP_REASON="discard_after_failure"
-    rm -rf "$TMP_DIR"
+    clear_dir_contents "$TMP_DIR"
     mkdir -p "$TMP_DIR"
     TMP_CLEANUP_STATUS="discarded_recreated"
   else