[v23.2.x] c/archival_stm: do not reset _last_replicate on timeout

[vbotbuildovich]

Backport #15677 to branch v23.2.x. Note that this issue was created as a placeholder, since the original PR's commit(s) could not be automatically cherry-picked.
Here are the commands to execute:

git checkout v23.2.x
git checkout -b vbotbuildovich/backport-15677-v23.2.x-768
git cherry-pick -x 299e12dfb241df84068395c1568f357a1e16ddda

git push origin vbotbuildovich/backport-15677-v23.2.x-768
gh pr create \
  --title "[v23.2.x] c/archival_stm: do not reset _last_replicate on timeout" \
  --base "v23.2.x" \
  --label "kind/backport" \
  --head "vbotbuildovich/backport-15677-v23.2.x-768" \
  --draft \
  --repo "redpanda-data/redpanda" \
  --reviewer "Lazin" \
  --milestone "v23.2.x-next" \
  --body "Backport of PR https://github.com/redpanda-data/redpanda/pull/15677 "

[nvartolomei]

#15816