Removing unused rule data client

[ymao1]

Summary

Followup to #192576. RuleDataClient is no longer used by observability rules since they're not using the lifecycle executor so we can remove the initialization logic.

[elasticmachine]

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[elasticmachine]

💔 Build Failed

• Buildkite Build
• Commit: abf29dc

Failed CI Steps

• FTR Configs #89
• FTR Configs #89

Test Failures

• [job] [logs] FTR Configs #89 / rules security and spaces enabled: basic Alert - Get feature ids by registration context Users: obs_only_all_spaces_all should be able to get feature id for registration context 'observability.apm' in space1
• [job] [logs] FTR Configs #89 / rules security and spaces enabled: basic Alert - Get feature ids by registration context Users: obs_only_all_spaces_all should be able to get feature id for registration context 'observability.apm' in space1

Metrics [docs]

Unknown metric groups

ESLint disabled line counts

id	before	after	diff
infra	42	40	-2

Total ESLint disabled count

id	before	after	diff
infra	51	49	-2

History

• 💔 Build #251021 failed 8219edd