[ILM] Fix Index Management not loading when ILM enricher errors out

[jen-huang]

Fixes #28087

On Cloud, Index Management fails to load. This fixes the issue by:

1. Only loading ILM data enricher for Index Management if the ILM UI is enabled (ILM UI is disabled by default on Cloud)
2. Adding handling for any data enrichers that error out

Locally, this can be tested by setting xpack.ilm.ui.enabled: false in kibana.yml and changing this request URL to /*/_ilm/somebadurl. Without this fix, observe that Index Management page shows no indices (no system indices either) and displays an error toast. After applying this fix, page should function normally.

In addition, I also found that ILM is extending Index Management UI ("Add lifecycle policy" as a management option, etc) regardless of xpack.ilm.ui.enabled, I've adjust the extension registration so that they are only registered when UI is enabled.

[elasticmachine]

Pinging @elastic/es-ui

[elasticmachine]

💔 Build Failed

• continuous-integration/kibana-ci/pull-request

[jen-huang]

Failed on unrelated test (#27922):

12:49:26  FAIL  plugins/xpack_main/public/hacks/telemetry.test.js
12:49:26   ● telemetry class › _checkReportStatus › returns false if last report is too recent
12:49:26 
12:49:26     expect(received).toBe(expected) // Object.is equality
12:49:26 
12:49:26     Expected: false
12:49:26     Received: true
12:49:26 
12:49:26       132 |       const telemetry = new Telemetry(mockInjectorFromObject(injector), mockFetchTelemetry);
12:49:26       133 | 
12:49:26     > 134 |       expect(telemetry._checkReportStatus()).toBe(false);
12:49:26           |                                              ^
12:49:26       135 |     });
12:49:26       136 | 
12:49:26       137 |     test('returns true if last report is not defined', () => {
12:49:26 
12:49:26       at Object.toBe (plugins/xpack_main/public/hacks/telemetry.test.js:134:46)

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request

[bmcconaghy]

Code LGTM