index: remove unnecessary locater cleaning in BaseIndex::Init() #32882

1. 
   HowHsu commented at 4:13 pm on July 5, 2025: none

   BaseIndex::DB::ReadBestBlock() already cleans locater in failure path, remove duplicate code in the caller and change ReadBestBlock to return void.
2. index: remove unnecessary locater cleaning in BaseIndex::Init()

   BaseIndex::DB::ReadBestBlock() already cleans locater in failure path, remove
   duplicate code in the caller and change ReadBestBlock to return void.
   
   Signed-off-by: Hao Xu <hao.xu@linux.dev>

   1f678d832b
3. DrahtBot added the label UTXO Db and Indexes on Jul 5, 2025
4. 
   DrahtBot commented at 4:13 pm on July 5, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/32882.

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UTXO Db and Indexes