add compact for release-1.12

[changluyi]

• Make sure you have followed Kube-OVN Code Style.

What type of this PR

Examples of user facing changes:

• Features
• Bug fixes
• Docs
• Tests

Which issue(s) this PR fixes:

Fixes #(issue-number)

WHAT

🤖 Generated by Copilot at f163dae

This pull request adds a feature flag to enable or disable the OVN database compaction in the OVN leader checker. The feature flag is exposed as an environment variable and a command line argument in the OVN leader checker code, and as a Helm value and an environment variable in the central pod templates for different deployment scenarios.

🤖 Generated by Copilot at f163dae

Oh we are the OVN sailors, and we sail the network sea
We keep our databases tidy, with the ENABLE_COMPACT key
But not for every deployment, we have to check the mode
So haul away the leader checker, and set the proper code

HOW

🤖 Generated by Copilot at f163dae

• Add a new feature to enable or disable the OVN database compaction periodically (link, link, link, link, link, link, link, link)
• Add a new field networking.ENABLE_COMPACT to the default Helm values file charts/values.yaml with a default value of false (link)
• Add a new environment variable ENABLE_COMPACT to the central pod template in charts/templates/central-deploy.yaml and derive its value from the Helm values file (link)
• Add a new field EnableCompact to the Configuration type in pkg/ovn_leader_checker/ovn.go to store the value of the environment variable (link)
• Add a new flag --enableCompact to the OVN leader checker command line arguments in pkg/ovn_leader_checker/ovn.go and parse the value of the environment variable (link)
• Assign the value of the flag to the EnableCompact field in the configuration in pkg/ovn_leader_checker/ovn.go (link)
• Check the value of the EnableCompact field in the configuration and only call the compactOvnDatabase function for the OVN northbound and southbound databases if the field is true in the doOvnLeaderCheck function in pkg/ovn_leader_checker/ovn.go (link)
• Set the value of the ENABLE_COMPACT environment variable to false for the OVN-DPDK deployment in yamls/ovn-dpdk.yaml (link)
• Set the value of the ENABLE_COMPACT environment variable to false for the OVN-HA deployment in yamls/ovn-ha.yaml (link)