Drop trailing space from prefixes: get_indexing_prefix appends one

embeddinggemma-300m/config.json

@@ -4,6 +4,6 @@
   "vocab_md5": "00d2276cbec4474f6cf3df98fbc18cbb",
   "data_md5": "7cfd839859507c1b12041a6a0634ad19",
   "model_type": "gemma",
-  "indexing_prefix": "title: none | text: ",
-  "query_prefix": "task: search result | query: "
+  "indexing_prefix": "title: none | text:",
+  "query_prefix": "task: search result | query:"
 }