performance regression in power_by_squaring in julia 1.12

```
julia> @btime Base.power_by_squaring(m,2); setup=m=rand(1:10,100,100);
  130.965 &mu;s (3 allocations: 78.21 KiB)

julia> VERSION
v"1.11.5"
```

```
julia> @btime Base.power_by_squaring(m,2); setup=m=rand(1:10,100,100);
  262.153 &mu;s (6 allocations: 156.42 KiB)

julia> VERSION
v"1.12.0-beta4"
```