Remove "All" in applies_to

Considering the current state of our guidelines, we don't have a good reason for using "all" in applies_to.

- "All" refers to all versions, which we deal with by not specifying a version. Its meaning is ambiguous: "All" versions since when? Since the base version? Since version 1.0? This ambiguity opens doors for contributor and end user confusion.
- In the "$key: $lifecycle $version" pattern, only $key and $lifecycle are mandatory, and I think we're currently using a lot of "all" when it should be "ga" (we have a lot of "stack: all"). "All" is not a lifecycle state.

I'm proposing to eliminate its usage by fixing existing occurrences first, then to remove it from the system and guidelines.