Conflict resolution draft_commit_conflicts provides incorrect instructions

[korthout]

Describe the bug

The instructions to resolve the conflicts for draft pull requests are not correct:

Example:

git fetch origin stable/8.2
git worktree add -d .worktree/backport-18860-to-stable/8.2 origin/stable/8.2
cd .worktree/backport-18860-to-stable/8.2
git switch backport-18860-to-stable/8.2
git reset --hard HEAD^
git cherry-pick -x c2fbff443d734c9ed1a63fd0f3205b116b89ba38 55de7bf4ee62a549e1e83a78097903151210bd6e
git push --force-with-lease

This instructs to checkout origin/stable/8.2 and then switch to backport-18860-to-stable/8.2, but without fetching backport-18860-to-stable/8.2 this will fail.

To Reproduce
Steps to reproduce the behavior:

1. Set conflict_resolution to draft_commit_conflicts
2. Create and merge a pull request that results in a conflicts when backporting
3. Trigger the backport workflow
4. Notice the draft pull request with incorrect instructions.

Expected behavior
We should propose the following instructions:

git fetch origin <backportbranch>
git worktree add --checkout .worktree/<backportbranch> <backportbranch>
cd .worktree/<backportbranch>
git reset --hard HEAD^
git cherry-pick -x <commits>
git push --force-with-lease

Examples

• [Backport stable/8.3] Enable improved conflict resolution for backports camunda/camunda#18888
• [Backport stable/8.2] Enable improved conflict resolution for backports camunda/camunda#18887