docs: Add recent releases to documentation versions list

[Bouncheck]

Created some branches for those versions according to existing format. Note that scylla-4.19.0.x corresponds to the latest released 4.19.0.1 and not current master (scylla-4.x).
If the next released version is 4.19.0.2 then scylla-4.19.0.x will need to be moved with whatever documentation backports it has on top of 4.19.0.2. However it's unlikely that 4.19.0.2 will not have the same changes already, so it should not be an issue.

[Bouncheck]

Now it builds multiversionpreview however scylla-4.19.0.x and scylla-4.18.1.x have more broken documentations than previous versions. I see generally more warning when building and I see that "Manual" section does not have subsections where it does for 4.17.0.x.

[Bouncheck]

Created #542, #543, #545, #546 that adjust specific versions. Those should be merged in before this one.
Note that all of those versions will be added to scylladb_markdown_recommonmark_versions in conf.py here and if any was already adjusted to use {eval-rst} directive it will move back to using eval_rst in manual files.
This is due to the fact that when using myst with current configuration it treats relative links in the manuals as anchors.
Treating them as anchors does not redirect to any subpages which is an important downgrade.
This also means that after the changes in these PRs, when building locally documentation for an individual branch the process will fail to build the correct documentation tree, but it will still work for multiversion and multiversionpreview targets which is what matters for publishing new documentation right now.

[Bouncheck]

Verified by running make multiversionpreview with branches in conf.py limited to

    'scylla-4.15.0.x',
    'scylla-4.17.0.x',
    'scylla-4.18.1.x',
    'scylla-4.19.0.x'