kernel: Remove unnecessary blockfilter{index,}.cpp

It is no longer necessary to link in blockfilter.cpp and
index/blockfilterindex.cpp after merge of PR#21726 since validation has
been decouple from the blockfilterindex.

Author: dongcarl

src/Makefile.am

@@ -853,7 +853,6 @@ endif
 libbitcoinkernel_la_SOURCES = \
   kernel/bitcoinkernel.cpp \
   arith_uint256.cpp \
-  blockfilter.cpp \
   chain.cpp \
   chainparamsbase.cpp \
   chainparams.cpp \
@@ -872,7 +871,6 @@ libbitcoinkernel_la_SOURCES = \
   fs.cpp \
   hash.cpp \
   index/base.cpp \
-  index/blockfilterindex.cpp \
   index/coinstatsindex.cpp \
   init/common.cpp \
   key.cpp \