[Infra UI] Adapt to Elasticsearch total hit count response format change

[weltenwort]

Once elastic/elasticsearch#35849 is merged into master, any usages of the hit count will fail. There are two steps we should take to mitigate this:

1. Force the response to match the previous format by adding rest_total_hits_as_int=true as a query parameter to the requests in both master and 6.x. (PR [Infra UI] pass flag in request to force BWC hit count #26517)
2. While this means there is no divergence between master and 6.x for now, it will have to be replaced with the new format before 8.0.0. This will happen in [Infra UI] Remove deprecated total_hits request parameter #29435.

Current usages

• https://github.com/elastic/kibana/blob/970dcb5030fe06af3fe4493c7fc2b85da21c3199/x-pack/plugins/infra/server/lib/adapters/metrics/lib/check_valid_node.ts

[elasticmachine]

Pinging @elastic/infrastructure-ui

[alvarolobato]

The second bullet will be executed after the 7.0 branch is created.

[weltenwort]

The second step is tracked in #29435.