[Offers] Total offers field is not recalculated after deleting an offer

**Description:** Total offers field is not recalculating after deleting an offer. (look into hooks in Offer model)

**Reproducible:** always.

**Preconditions:**
The user is logged in.

**Steps to reproduce:**
1. Delete an offer.

**Actual result:**
Total offers quantity is not changed.

**Expected result:**
Total offers quantity must be changed.