Enable caching for search results view

[Ambient-Impact]

The view currently has caching set to none to work around the problem that the Search API excerpt gets cached for a given highlight the first time it's viewed when set to tag-based caching. This issue was surfaced when running the database update introduced in Wrong query type & cache type on Search API Views [#3196990] via search_api-8.x-1.24.

Investigation should be done into how to vary the excerpt by the terms used, presumably via cache contexts. Re-rendering the view for every search performed will not scale well and puts unnecessary load on the server.

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December 2022 update: this is beginning to be a bigger issue as search results can take quite a while generate and sometimes cause submitting the search form to hit the PHP time limit. There are two main issues here:

1. The Search API module doesn't seem to vary search results caching by search terms. There's an open issue to address this.
2. There's potentially a lot more rendering happening than is expected based on content that should already be rendered and indexed.

Both of these need to be implemented/fixed to allow caching to work correctly.