WT-12954: optimizing Cluster performance jitter caused by checkpoint

[y123456yz]

Today, a user encountered a similar issue，they put a lot of pressure on us and requested us to resolve it within a week. I want to solve it by limiting the checkpoint speed, but I am not sure if this will solve the problem, and I am concerned about bugs in my code. Therefore, I need your help to ensure that everything is safe.

Through this PR, we can limit the checkpoint speed of MongoDB by using the following command：
db.adminCommand( { setParameter : 1, "wiredTigerEngineRuntimeConfig" : "io_capacity=(checkpoint=1M)"})

If convenient, please prioritize processing this PR, thank you.

[wiredtiger-pr-bot]

Hi @y123456yz, thank you for your submission!
Please make sure to sign our Contributor Agreement (if you haven't already) and provide us with editor permissions on your branch. Instructions on how do that can be found here.

[y123456yz]

Background:
We have many low-level MongoDB instances on the cloud, such as 2C4G When a checkpoint cycle writes QPS slightly higher, we often encounter the following problems:

1. CPU burrs and jitter
2. Slow queries affecting business

By analyzing diagnose.data, it is confirmed that the main cause is checkpoint, which is basically completed in seconds. This is the root cause of the problem
This PR mainly limits the write speed of checkpoint io to ensure smoother and more stable checkpoints

Looking at the historical MongoDB user work orders, we found that this issue exists in at least dozens of user clusters, not including clusters where users have not reported any issues. There are actually more clusters with this issue.

[y123456yz]

WT-12954

[y123456yz]

May I ask: This PR needs to add a use case for io_capacity.checkpoint, which is similar to the test case for WT-11877. However, I found that WT-11877 was Revert, and I think PR(WT-11877) is meaningful. We need to solve the testing script's bug for PR(WT-11877). What should I do better here?