Make sure every conditional branch constructed by `LoopUnrollRuntime` code sets branch weights.

- Add new 1:127 weights for the conditional jumps checking whether the whole (unrolled) loop should be skipped in the generated prolog or epilog code.
- Remove
`updateLatchBranchWeightsForRemainderLoop`function and just add weights immediately when constructing the relevant branches. This leads to simpler code and makes the code more obvious as every call to`CreateCondBr`now has a`BranchWeights`parameter. - Rework formula for epilogue latch weights, to assume equal distribution of remainders and remove
`assert`(as I was able to reach this code when forcing small unroll factors on the commandline).