Simplify more specialized control decompositions using `Always` metabloq.

[anurudhp]

See the Always metabloq introduced in: #1605

The two known patterns where this is useful:

1. Compute-uncompute pairs (for an example, see HamiltonianSimulationByGQSP)
2. Controlled-loading (for an example, see AddK)

E.g. a lot of the LCU bloqs can benefit from this.