fix update snat rules not effect correctly

[qiutingjun]

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

What type of this PR

Examples of user facing changes:

• Bug fixes

While update the internal CIDR of the snat rule, it will not really take effect in the vpc nat gateway pod, the rule k8s shows does not match the actual rule in gateway pod.

[github-actions]

• The commit message should be more descriptive and informative.
• There are no potential bugs or format errors in the code patch.
• There is a performance issue in the handleUpdateIptablesSnatRule function where it deletes and creates SNAT rules even if there is no change in the internal CIDR. This can be optimized to avoid unnecessary operations.
• The code can be improved by adding comments to explain the purpose of each function and variable.

[hongzhen-ma]

上边机器人 review意见第三条
There is a performance issue in the handleUpdateIptablesSnatRule function where it deletes and creates SNAT rules even if there is no change in the internal CIDR. This can be optimized to avoid unnecessary operations.

是否需要考虑下？
这个如果考虑修改的话，可以等合入之后，一起看下 dnat snat 和 fip 的处理。

[qiutingjun]

上边机器人 review意见第三条 There is a performance issue in the handleUpdateIptablesSnatRule function where it deletes and creates SNAT rules even if there is no change in the internal CIDR. This can be optimized to avoid unnecessary operations.

是否需要考虑下？

The rule has been checked by function 'enqueueUpdateIptablesSnatRule'.If there is no changes it will not be passed here for processing.