Fix FTS index creation crash when using dict-based workload FTS config

workload.get("FTS") returns {"num_indexes": N, "num_queries": N} but
code used integer index [0] instead of the key name.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Change-Id: I992080ebbea25f85370f74453f7e235cad86fcd2
Reviewed-on: https://review.couchbase.org/c/TAF/+/245270
Tested-by: Build Bot <build@couchbase.com>
Tested-by: Ashwin <ashwin.govindarajulu@couchbase.com>
Reviewed-by: <shiva.adky@couchbase.com>

Author: ashwin2002

pytests/aGoodDoctor/fts.py

@@ -129,7 +129,7 @@ def create_fts_indexes(self, cluster, dims=1536, similarity="l2_norm", _type="ve
                     if valType == "NimbusM":
                         queryTypes = NimbusMQueries
                     i = 0
-                    while i < workload.get("FTS")[0]:
+                    while i < workload.get("FTS")["num_indexes"]:
                         name = str(b.name).replace("-", "_") + c + "_fts_idx_"+str(i)
                         fts_param_template = deepcopy(template)
                         fts_param_template.update({