Bump ZooKeeper to 3.9.6 and zookeeper-operator to 0.2.15-adobe-20260924

[francoisferrand]

Adobe released zookeeper-operator 0.2.15-adobe-20260924, which supports ZooKeeper 3.9.6.
Build our ZooKeeper image from 3.9.6 with the zu tool and scripts from the new operator tag, and use the matching operator chart in the kind e2e setup.

Issue: ZENKO-5374

[bert-e]

Hello francoisferrand,

My role is to assist you with the merge of this
pull request. Please type @bert-e help to get information
on this process, or consult the user documentation.

Available options

name	description	privileged	authored
/after_pull_request	Wait for the given pull request id to be merged before continuing with the current one.
/bypass_author_approval	Bypass the pull request author's approval	⭐
/bypass_build_status	Bypass the build and test status	⭐
/bypass_commit_size	Bypass the check on the size of the changeset TBA	⭐
/bypass_incompatible_branch	Bypass the check on the source branch prefix	⭐
/bypass_jira_check	Bypass the Jira issue check	⭐
/bypass_peer_approval	Bypass the pull request peers' approval	⭐
/bypass_leader_approval	Bypass the pull request leaders' approval	⭐
/bypass_source_branch_lineage	Bypass the cross-branch contamination check	⭐
/approve	Instruct Bert-E that the author has approved the pull request.		✍️
/create_pull_requests	Allow the creation of integration pull requests.
/create_integration_branches	Allow the creation of integration branches.
/no_octopus	Prevent Wall-E from doing any octopus merge and use multiple consecutive merge instead
/unanimity	Change review acceptance criteria from one reviewer at least to all reviewers
/wait	Instruct Bert-E not to run until further notice.

Available commands

name	description	privileged
/help	Print Bert-E's manual in the pull request.
/status	Print Bert-E's current status in the pull request.
/clear	Remove all comments from Bert-E from the history TBA
/retry	Re-start a fresh build TBA
/build	Re-start a fresh build TBA
/force_reset	Delete integration branches & pull requests, and restart merge process from the beginning.
/reset	Try to remove integration branches unless there are commits on them which do not appear on the source branch.

Status report is not available.

[bert-e]

Waiting for approval

The following approvals are needed before I can proceed with the merge:

• the author

• 2 peers

[francoisferrand]

/approve

[bert-e]

I have successfully merged the changeset of this pull request
into targetted development branches:

• ✔️ development/2.16

The following branches have NOT changed:

• development/2.10
• development/2.11
• development/2.12
• development/2.13
• development/2.14
• development/2.15
• development/2.5
• development/2.6
• development/2.7
• development/2.8
• development/2.9

This pull request did not target the following hotfix branch(es) so they
were left untouched:

• hotfix/2.13.5

Please check the status of the associated issue ZENKO-5374.

Goodbye francoisferrand.

The following options are set: approve