Shrink index operation: minor change after bugathon and review

[gaobinlong]

There are some minor bugs after bugathon and team members' review, we need to fix them.

[gaobinlong]

These work need to be done for the shrink index page:

1. Add a space before the learn more link.
2. Modify the format of the title.

[gaobinlong]

There is a pre-check which is not accurate for the shrink index operation, when a copy of every shard of the source index do not reside on the same node, currently a warning will be shown when the shrink index page appears, but the check is not accurate because there are no direct way to check whether a copy of every shard reside on the same node. So the check will be removed, and the OpenSearch server will return any error message when then shrink api call fails.

[gaobinlong]

Besides, there are some wording need to be correct, such as change Green to green in the error message.