[Index management] Make UI resilient to failing _cat/aliases call

[sebelga]

In order to build the table of indices in Index Management, we make 2 requests to Elasticsearch

GET _cat/indices
GET _cat/aliases

But there is a bug in ES (elastic/elasticsearch#46856) that requires the manage privilege on all indices ("*") in order to execute the _cat/aliases. Otherwise it throws the following error

{
  "error" : {
    "root_cause" : [
      {
        "type" : "index_not_found_exception",
        "reason" : "no such index",
        "index_uuid" : "_na_",
        "index" : "_all"
      }
    ],
    "type" : "index_not_found_exception",
    "reason" : "no such index",
    "index_uuid" : "_na_",
    "index" : "_all"
  },
  "status" : 404
}

This means that, if a user does not have that privilege, the table does not render any indices and the following toast message is displayed

As displaying the aliases information is an enrichment of the index data, we should make our UI resilient to the fact that aliases haven't been fetched.

// x-pack/plugins/index_management/server/lib/fetch_indices.js

export const fetchIndices = async (callWithRequest, isEsError, indexNames) => {
  try {
    // We should **not** throw if this fetchAliases call fails
    const aliases = await fetchAliases(callWithRequest);
    const hits = await fetchIndicesCall(callWithRequest, indexNames);

And then update the UI accordingly to display or not the aliases information.

[elasticmachine]

Pinging @elastic/es-ui

[albertzaharovits]

@sebelga I was amiss with regard to the privileges required for some of the actions.
To be clear:
GET _cat/indices - requires view_index_metadata and monitor index privileges as well as the monitor cluster privilege.
GET _cat/aliases - requires the view_index_metadata index privilege.

[sebelga]

@albertzaharovits ok thanks for clarifying!

[yuliacech]

Closing this issue because Index Management doesn't make any calls to _cat APIs anymore