Update release block footer to show "Released at" when releases are sorted by release date

Release notes

When the Releases page is sorted by "Released date", update the UI text in each release block to show the released date.

Problem to solve

With the changes introduced in !43963 (merged), we can sort releases by their "Released date".

Proposal

The UI text in release_block_footer.vue should change from showing Created {time ago} to showing Released {time ago} when the Releases page is sorted by "Released date" as discussed here: !43963 (comment 443244743)

Screenshot