hugolib: Compare every element in pages cache

hugolib: Compare every element in pages cache

It is slightly slower, but correctnes is, of course, more important:

```bash
benchmark                             old ns/op     new ns/op     delta
BenchmarkSortByWeightAndReverse-4     367           645           +75.75%

benchmark                             old allocs     new allocs     delta
BenchmarkSortByWeightAndReverse-4     2              2              +0.00%

benchmark                             old bytes     new bytes     delta
BenchmarkSortByWeightAndReverse-4     64            64            +0.00%
```

Running the same benchmark without any cache (i.e. resorting the slice on every iteration) and then compare it to the current version shows that it still is plenty worth it:

```bash
▶ benchcmp 2.bench 1.bench
benchmark                             old ns/op     new ns/op     delta
BenchmarkSortByWeightAndReverse-4     1358757       645           -99.95%

benchmark                             old allocs     new allocs     delta
BenchmarkSortByWeightAndReverse-4     17159          2              -99.99%

benchmark                             old bytes     new bytes     delta
BenchmarkSortByWeightAndReverse-4     274573        64            -99.98%
```

Closes #5239