Change dropindex() to use FT.DROPINDEX (instead FT.DROP)

[dvora-h]

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Description of change

Fixes #2265

[codecov-commenter]

Codecov Report

Merging #2315 (26a2028) into master (f9f9d06) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2315      +/-   ##
==========================================
+ Coverage   92.08%   92.16%   +0.07%     
==========================================
  Files         109      110       +1     
  Lines       28241    28651     +410     
==========================================
+ Hits        26005    26405     +400     
- Misses       2236     2246      +10     

Impacted Files	Coverage Δ
redis/commands/search/commands.py	89.10% <100.00%> (+0.02%)	⬆️
redis/cluster.py	89.85% <0.00%> (-0.53%)	⬇️
tests/test_cluster.py	96.96% <0.00%> (-0.12%)	⬇️
redis/commands/core.py	82.11% <0.00%> (ø)
redis/commands/redismodules.py	100.00% <0.00%> (ø)
tests/test_asyncio/test_graph.py	99.22% <0.00%> (ø)
tests/test_asyncio/test_cluster.py	97.41% <0.00%> (+0.13%)	⬆️
redis/commands/graph/commands.py	85.71% <0.00%> (+0.90%)	⬆️
redis/commands/graph/__init__.py	94.77% <0.00%> (+2.38%)	⬆️
redis/commands/graph/query_result.py	93.81% <0.00%> (+2.49%)	⬆️

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[chayim]

Any idea when FT.DROP vs DROPINDEX happened?

[dvora-h]

FT.DROP is deprecated