Interference effects for H→WW→ℓνqq¯′$$ H\to W\;W\to \ell \nu q{\overline{q}}^{\prime } $$ and H→ZZ→ℓℓ¯qq¯$$ H\to ZZ\to \ell \overline{\ell}q\overline{q} $$ searches in gluon fusion at the LHC