Move RBF-bump to start of update_claims_view to avoid double-bump

Move RBF-bump to start of update_claims_view to avoid double-bump

`OnchainTx::update_claims_view` currently checks if there are
packages which need to be RBF-bumped first, prior to adding new
packages to the tracking map. This can, in some cases, cause us to
RBF-bump a package which we only just added, at least in cases
where we're skipping blocks being connected.

Here we simply move the RBF-bump check to the top of
`OnchainTx::update_claims_view`, avoiding any such cases (though
there are still some cases where we may call
`OnchainTx::update_claims_view` twice for the same block, which is
resolved separately).