On LMDB, after an update the impact VLV index, the vlv recno cache is not systematically cleared

[tbordaz]

Issue Description
The VLV manages/uses an index database. In LMDB in addition to the index there is one 'recno cache' database per VLV index. This recno cache, related to a given VLV index, is cleared when an update impacts the VLV index.
The recno cache is not systematically cleared upon update of the VLV index

Package Version and Platform:

• since 2.5

Steps to Reproduce
install ipa-server and run test_xmlrpc/test_cert_plugin.py in a loop (see IDMDS-4688)
symptoms are

• search failure 'RESULT err=1 tag=101 nentries=0'
• 'ERR - vlv_build_idl - Can't follow db cursor (err -12797)'

Expected results
VLV search should not fail