Let $A$ and $B$ are $3\times 3$ matrices with real number entries, where $A$ is symmetric, $B$ is skew-symmetric and $\left(A+B\right)\left(A-B\right)=\left(A-B\right)\left(A+B\right)$. If ${\left(AB\right)}^T={\left(-1\right)}^{k}AB$, then the sum of all possible integral value of $k$ in $\left[2,10\right]$ is equal to (where $A^T$ represent transpose of matrix $A$)