mod: remove local replace for healthcheck module

With the new healthcheck/v1.2.2 tag pushed, we can finally remove the
local replace directive.

go.mod

@@ -65,9 +65,6 @@ require (
 	gopkg.in/macaroon.v2 v2.0.0
 )
 
-// TODO(guggero): Remove these after merging #6350 and pushing the new tag!
-replace github.com/lightningnetwork/lnd/healthcheck => ./healthcheck
-
 // This replace is for https://github.com/advisories/GHSA-w73w-5m7g-f7qc
 replace github.com/dgrijalva/jwt-go => github.com/golang-jwt/jwt v3.2.1+incompatible